C28x Piccolo Workshop

C2000™ Piccolo™ Workshop

Workshop Guide and Lab Manual

Technical Training

Organization

F28xPmdw Revision 1.0 September 2009

Important Notice

Important Notice Texas Instruments and its subsidiaries (TI) reserve the right to make changes to their products or to discontinue any product or service without notice, and advise customers to obtain the latest version of relevant information to verify, before placing orders, that information being relied on is current and complete. All products are sold subject to the terms and conditions of sale supplied at the time of order acknowledgment, including those pertaining to warranty, patent infringement, and limitation of liability.

TI warrants performance of its semiconductor products to the specifications applicable at the time of sale in accordance with TI’s standard warranty. Testing and other quality control techniques are utilized to the extent TI deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily performed, except those mandated by government requirements.

Customers are responsible for their applications using TI components.

In order to minimize risks associated with the customer’s applications, adequate design and operating safeguards must be provided by the customer to minimize inherent or procedural hazards.

TI assumes no liability for applications assistance or customer product design. TI does not warrant or represent that any license, either express or implied, is granted under any patent right, copyright, mask work right, or other intellectual property right of TI covering or relating to any combination, machine, or process in which such semiconductor products or services might be or are used. TI’s publication of information regarding any third party’s products or services does not constitute TI’s approval, warranty or endorsement thereof.

Copyright © 2009 Texas Instruments Incorporated

Revision History September 2009 – Revision 1.0

Mailing Address Texas Instruments Training Technical Organization 7839 Churchill Way M/S 3984 Dallas, Texas 75251-1903

ii C2000 Piccolo Workshop - Introduction




Texas InstrumentsTechnical Training

Copyright © 2009 Texas Instruments. All rights reserved.Technical TrainingOrganization

T TOC2000 and Piccolo are trademarks of Texas Instruments.

Introductions

Introductions

NameCompanyProject ResponsibilitiesDSP / Microcontroller ExperienceTMS320 Processor ExperienceHardware / Software - Assembly / CInterests

C2000 Piccolo Workshop - Introduction iii


C2000™ Piccolo™ Workshop Outline

C2000™ Piccolo™ Workshop Outline1. Architecture Overview2. Programming Development Environment

Lab: Linker command file3. Peripheral Register Header Files4. Reset and Interrupts5. System Initialization

Lab: Watchdog and interrupts6. Analog-to-Digital Converter

Lab: Build a data acquisition system7. Control Peripherals

Lab: Generate and graph a PWM waveform8. Numerical Concepts and IQ Math

Lab: Low-pass filter the PWM waveform9. Control Law Accelerator (CLA)

Lab: Use CLA to filter PWM waveform10. System Design

Lab: Run the code from flash memory11. Communications12. DSP/BIOS

Lab: Run DSP/BIOS code from flash memory13. Support Resources

C2000™ Experimenter Kit

Piccolo™ Experimenter Kit

ControlCARD

USB Docking Station

iv C2000 Piccolo Workshop - Introduction

Architecture Overview

Introduction This architectural overview introduces the basic architecture of the C2000™ Piccolo™ series of microcontrollers from Texas Instruments. The Piccolo™ series adds a new level of general purpose processing ability unseen in any previous DSP/MCU chips. The C2000™ is ideal for applications combining digital signal processing, microcontroller processing, efficient C code execution, and operating system tasks.

Unless otherwise noted, the terms C28x, F28x and F2803x refer to TMS320F2803x devices throughout the remainder of these notes. For specific details and differences please refer to the device data sheet and user’s guide.

Learning Objectives When this module is complete, you should have a basic understanding of the F28x architecture and how all of its components work together to create a high-end, uniprocessor control system.

Learning Objectives

Review the F28x block diagram and device featuresDescribe the F28x bus structure and memory mapIdentify the various memory blocks on the F28xIdentify the peripherals available on the F28x

C2000 Piccolo Workshop - Architecture Overview 1 - 1

Module Topics

Module Topics Architecture Overview.............................................................................................................................. 1-1

Module Topics......................................................................................................................................... 1-2 What is the TMS320C2000™?................................................................................................................ 1-3

TMS320C2000™ Internal Bussing .................................................................................................... 1-4 F28x CPU ............................................................................................................................................... 1-5

Special Instructions............................................................................................................................. 1-6 Pipeline Advantage............................................................................................................................. 1-7

Memory ................................................................................................................................................... 1-8 Memory Map ...................................................................................................................................... 1-8 Code Security Module (CSM)............................................................................................................ 1-9 Peripherals .......................................................................................................................................... 1-9

Fast Interrupt Response .........................................................................................................................1-10 F28x Mode .............................................................................................................................................1-11 Reset.......................................................................................................................................................1-12 Summary ................................................................................................................................................1-13

1 - 2 C2000 Piccolo Workshop - Architecture Overview

What is the TMS320C2000™?

What is the TMS320C2000™? The TMS320C2000™ is a 32-bit fixed point microcontroller that specializes in high performance control applications such as, robotics, industrial automation, mass storage devices, lighting, optical networking, power supplies, and other control applications needing a single processor to solve a high performance application.

TMS320F2803x Block Diagram

32x32 bitMultiplier

SectoredFlash

Program Bus

Data Bus

RAMBootROM

32-bitAuxiliaryRegisters

332-bit

Timers

Real-TimeJTAG

Emulation CPURegister Bus

R-M-WAtomic

ALU

PIE Interrupt Manager

eQEP

12-bit ADC

Watchdog

CAN 2.0B

I2C

SCI

SPI

GPIO

ePWM

eCAP

CLA

LIN

CLA Bus

The F2803x architecture can be divided into 3 functional blocks:

• CPU and busing

• Memory

• Peripherals


What is the TMS320C2000™?

TMS320C2000™ Internal Bussing As with many DSP-type devices, multiple busses are used to move data between the memories and peripherals and the CPU. The F28x memory bus architecture contains:

• A program read bus (22-bit address line and 32-bit data line)

• A data read bus (32-bit address line and 32-bit data line)

• A data write bus (32-bit address line and 32-bit data line)

Program-read Data Bus (32)

F28x CPU Internal Bus Structure

Data-write Address Bus (32)

Program Address Bus (22)

Execution

R-M-WAtomic

ALU

Real-TimeJTAG

Emulation

Program

DecoderPC

XAR0to

XAR7

SPDP @X

ARAU MPY32x32

XTP

ACC

ALU

Registers Debug

Register Bus / Result Bus

Data/Program-write Data Bus (32)

Data-read Address Bus (32)

Data-read Data Bus (32)

CLA

ProgramMemory

DataMemory

Peripherals

ExternalInterface

The 32-bit-wide data busses enable single cycle 32-bit operations. This multiple bus architecture, known as a Harvard Bus Architecture enables the F28x to fetch an instruction, read a data value and write a data value in a single cycle. All peripherals and memories are attached to the memory bus and will prioritize memory accesses.


F28x CPU

F28x CPU The F28x is a highly integrated, high performance solution for demanding control applications. The F28x is a cross between a general purpose microcontroller and a digital signal processor, balancing the code density of a RISC processor and the execution speed of a DSP with the architecture, firmware, and development tools of a microcontroller.

The DSP features include a modified Harvard architecture and circular addressing. The RISC features are single-cycle instruction execution, register-to-register operations, and a modified Harvard architecture. The microcontroller features include ease of use through an intuitive instruction set, byte packing and unpacking, and bit manipulation.

F28x and CLAMCU/DSP balancing code density & execution time

16-bit instructions for improved code density32-bit instructions for improved execution time

32-bit fixed-point CPU 32x32 fixed-point MAC, doubles as dual 16x16 MACParallel processing Control Law Accelerator (CLA) adds IEEE Single-precision 32-bit floating point math operationsCLA algorithm execution is independent of the main CPUFast interrupt service timeSingle cycle read-modify-write instructionsUnique real-time debugging capabilities

Data Bus

332-bit

TimersCPU

Register Bus

Program Bus

PIE Interrupt Manager32x32 bit

Multiplier

32-bitAuxiliaryRegisters

R-M-WAtomic

ALUCLA

CLA Bus

The F28x design supports an efficient C engine with hardware that allows the C compiler to generate compact code. Multiple busses and an internal register bus allow an efficient and flexible way to operate on the data. The architecture is also supported by powerful addressing modes, which allow the compiler as well as the assembly programmer to generate compact code that is almost one to one corresponded to the C code.

The F28x is as efficient in DSP math tasks as it is in system control tasks. This efficiency removes the need for a second processor in many systems. The 32 x 32-bit MAC capabilities of the F28x and its 64-bit processing capabilities, enable the F28x to efficiently handle higher numerical resolution problems that would otherwise demand a more expensive solution. Along with this is the capability to perform two 16 x 16-bit multiply accumulate instructions simultaneously or Dual MACs (DMAC). Also, some devices feature a floating-point unit.

The, F28x is source code compatible with the 24x/240x devices and previously written code can be reassembled to run on a F28x device, allowing for migration of existing code onto the F28x.


F28x CPU

Special Instructions

F28x Atomic Read/Modify/Write

Registers ALU / MPY

LOAD

STORE

WRITE

READ

CPU Mem

Atomic Instructions Benefits:

Simpler programming

Smaller, faster code

Uninterruptible (Atomic)

More efficient compiler

AND *XAR2,#1234h

2 words / 1 cycles

Atomic Read/Modify/Write

MOV AL,*XAR2AND AL,#1234hMOV *XAR2,AL

DINT

EINT

6 words / 6 cycles

Standard Load/Store

Atomics are small common instructions that are non-interuptable. The atomic ALU capability supports instructions and code that manages tasks and processes. These instructions usually execute several cycles faster than traditional coding.


F28x CPU

Pipeline Advantage

F1 F2 D1 D2 R1 R2 E

F28x Pipeline

Protected Pipeline

Order of results are as written in source code

Programmer need not worry about the pipeline

8-stage pipelineF1 F2 D1 D2 R1 R2 E

F1 F2 D1 D2 R1 R2 E

F1 F2 D1 D2 R1 R2 E

F1 F2 D1 D2 R1 R2 E

F1 F2 D1 D2 R1 R2 E

F1 F2 D1 D2 R1 R2 E

F1 F2 D1 D2 R1 R2 E

ABC

DEFG

W

W

W

W

W

W

W

W

E & G Accesssame address

R1 R2 E W

D2 R1 R2 E W

F1: Instruction AddressF2: Instruction ContentD1: Decode InstructionD2: Resolve Operand AddrR1: Operand AddressR2: Get OperandE: CPU doing “real” workW: store content to memory

H

The F28x uses a special 8-stage protected pipeline to maximize the throughput. This protected pipeline prevents a write to and a read from the same location from occurring out of order.

This pipelining also enables the F28x to execute at high speeds without resorting to expensive high-speed memories. Special branch-look-ahead hardware minimizes the latency for conditional discontinuities. Special store conditional operations further improve performance.


Memory

Memory The memory space on the F28x is divided into program memory and data memory. There are several different types of memory available that can be used as both program memory and data memory. They include the flash memory, single access RAM (SARAM), OTP, and Boot ROM which is factory programmed with boot software routines or standard tables used in math related algorithms.

Memory Map The F28x CPU contains no memory, but can access memory on chip. The F28x uses 32-bit data addresses and 22-bit program addresses. This allows for a total address reach of 4G words (1 word = 16-bits) in data memory and 4M words in program memory. Memory blocks on all F28x designs are uniformly mapped to both program and data space.

This memory map shows the different blocks of memory available to the program and data space.

TMS320F28035 Memory Map

0x0000000x0004000x000800

M1 SARAM (1Kw)M0 SARAM (1Kw)Data Program

PIE Vectors(256 w)

PF 0 (6Kw)reserved

PF 1 (4Kw)PF 2 (4Kw)

L0 SARAM (2Kw)L1 DPSARAM (1Kw)L2 DPSARAM (1Kw)L3 DPSARAM (4Kw)

0x000D00

0x0020000x0060000x0070000x0080000x0088000x008C00

0x00A000

0x000E00

0x009000

0x3D78000x3D7C000x3D7C80

reserved

Data Program

FLASH (64Kw)

PASSWORDS (8w)

User OTP (1Kw)

0x3D80000x3D7C80

0x3E8000

Boot ROM (8Kw)

L0 SARAM (2Kw)reserved

0x3F7FF80x3F80000x3F88000x3FE000

0x3FFFFF

Dual Mapped: L0

CSM Protected:L0, L1, L2, L3, OTPFLASH, ADC CAL,Flash Regs in PF0

0x3FFFC0BROM Vectors (64w)

reserved

reserved

ADC / OSC cal. data

Dual-Port RAM: L1, L2 & L3(accessible by CPU & CLA)


Memory

Code Security Module (CSM)

Code Security ModulePrevents reverse engineering and protects valuable intellectual property

128-bit user defined password is stored in Flash128-bits = 2128 = 3.4 x 1038 possible passwordsTo try 1 password every 8 cycles at 60 MHz, it would take at least 1.4 x 1024 years to try all possible combinations!


User OTP (1Kw)

ADC / OSC cal. data

L0 SARAM (2Kw)

reserved

reservedDualMapped

FLASH (64Kw)PASSWORDS (8w)

reserved

0x0080000x0088000x008C00

0x00A0000x009000

0x3D78000x3D7C000x3D7C800x3D80000x3E80000x3F7FF80x3F80000x3F8800

Peripherals The F28x comes with many built in peripherals optimized to support control applications. These peripherals vary depending on which F28x device you choose.

• ePWM • SPI

• eCAP • SCI

• eQEP • I2C

• Analog-to-Digital Converter • LIN

• Watchdog Timer • CAN

• CLA • GPIO


Fast Interrupt Response

Fast Interrupt Response The fast interrupt response, with automatic context save of critical registers, resulting in a device that is capable of servicing many asynchronous events with minimal latency. F28x implements a zero cycle penalty to do 14 registers context saved and restored during an interrupt. This feature helps reduces the interrupt service routine overheads.

F28x Fast Interrupt Response Manager

96 dedicated PIE vectorsNo software decision making requiredDirect access to RAM vectorsAuto flags updateConcurrent auto context save

28x CPU Interrupt logic

28xCPUINTMIFR IER96

Per

iphe

ral I

nter

rupt

s 1

2x8

= 96

12 interrupts

INT1 to INT12

PIERegister

Map

PIE module For 96

interrupts

T ST0AH ALPH PLAR1 (L) AR0 (L)DP ST1DBSTAT IERPC(msw) PC(lsw)

Auto Context Save


F28x Mode

F28x Mode The F28x is one of several members of the TMS320 microcontroller family. The F28x is source code compatable with the 24x/240x devices and previously written code can be reassembled to run on a F28x device. This allows for migration of existing code onto the F28x.

F28x Operating Modes

C28x Native Mode 1 0

C24x Compatible Mode 1 1

Test Mode (default) 0 0

Reserved 0 1

OBJMODE AMODEMode Bits Compiler OptionMode Type

Almost all uses will run in C28x Native ModeThe bootloader will automatically select C28x Native Mode after resetC24x compatible mode is mostly for backwards compatibility with an older processor family

-v28 –m20

-v28


Reset

Reset Reset – Bootloader

TRST = JTAG Test ResetEMU_KEY & EMU_BMODE located in PIE at 0x0D00 & 0x0D01, respectively

Note:Details of the various boot options will be discussed in the Reset and Interrupts module

Boot ModeWait

The “wait” boot mode is used and the boot mode is determined by the debugger

Reset vector fetched from

boot ROM0x3F FFC0

Emulator Connected?

Bootloader setsOBJMODE = 1

AMODE = 0

Emulation BootBoot determined by

2 RAM locations:EMU_KEY and EMU_BMODE

TRST = 1

ResetOBJMODE = 0

AMODE = 0ENPIE = 0INTM = 1

YES


Summary

Summary Summary

High performance 32-bit CPU32x32 bit or dual 16x16 bit MACHardware Control Law Accelerator (CLA)Atomic read-modify-write instructionsFast interrupt response manager64Kw on-chip flash memoryCode security module (CSM)Control peripherals12-bit ADC moduleComparatorsUp to 44 shared GPIO pinsCommunications peripherals


Summary


Programming Development Environment

Introduction This module will explain how to use Code Composer Studio (CCS) integrated development environment (IDE) tools to develop a program. Creating projects and setting building options will be covered. Use and the purpose of the linker command file will be described.

Learning Objectives Learning Objectives

Use Code Composer Studio to:Create a ProjectSet Build Options

Create a user linker command file which:Describes a system’s available memoryIndicates where sections will be placed in memory

C2000 Piccolo Workshop - Programming Development Environment 2 - 1

Module Topics

Module Topics Programming Development Environment .............................................................................................. 2-1

Module Topics......................................................................................................................................... 2-2 Code Composer Studio ........................................................................................................................... 2-3

Software Development and COFF Concepts...................................................................................... 2-3 Projects ............................................................................................................................................... 2-5 Build Options...................................................................................................................................... 2-6

Creating a Linker Command File ........................................................................................................... 2-9 Sections .............................................................................................................................................. 2-9 Linker Command Files (.cmd) .........................................................................................................2-12 Memory-Map Description .................................................................................................................2-12 Section Placement..............................................................................................................................2-14

Exercise 2...............................................................................................................................................2-15 Summary: Linker Command File ......................................................................................................2-16

Lab 2: Linker Command File.................................................................................................................2-17 Solutions.................................................................................................................................................2-22

2 - 2 C2000 Piccolo Workshop - Programming Development Environment

Code Composer Studio


Software Development and COFF Concepts In an effort to standardize the software development process, TI uses the Common Object File Format (COFF). COFF has several features which make it a powerful software development system. It is most useful when the development task is split between several programmers.

Each file of code, called a module, may be written independently, including the specification of all resources necessary for the proper operation of the module. Modules can be written using Code Composer Studio (CCS) or any text editor capable of providing a simple ASCII file output. The expected extension of a source file is .ASM for assembly and .C for C programs.


Code Composer Studio includes:Integrated Edit/Debug GUICode Generation ToolsDSP/BIOS

Asm Link

Editor

Debug

Compile

Graphs,Profiling

CodeSimulator

eZdsp™

ExternalEmulator

MCUBoard

Libraries

lnk.cmdBuild

Code Composer Studio includes a built-in editor, compiler, assembler, linker, and an automatic build process. Additionally, tools to connect file input and output, as well as built-in graph displays for output are available. Other features can be added using the plug-ins capability

Numerous modules are joined to form a complete program by using the linker. The linker efficiently allocates the resources available on the device to each module in the system. The linker uses a command (.CMD) file to identify the memory resources and placement of where the various sections within each module are to go. Outputs of the linking process includes the linked object file (.OUT), which runs on the device, and can include a .MAP file which identifies where each linked section is located.

The high level of modularity and portability resulting from this system simplifies the processes of verification, debug and maintenance. The process of COFF development is presented in greater detail in the following paragraphs.



The concept of COFF tools is to allow modular development of software independent of hardware concerns. An individual assembly language file is written to perform a single task and may be linked with several other tasks to achieve a more complex total system.

Writing code in modular form permits code to be developed by several people working in parallel so the development cycle is shortened. Debugging and upgrading code is faster, since components of the system, rather than the entire system, is being operated upon. Also, new systems may be developed more rapidly if previously developed modules can be used in them.

Code developed independently of hardware concerns increases the benefits of modularity by allowing the programmer to focus on the code and not waste time managing memory and moving code as other code components grow or shrink. A linker is invoked to allocate systems hardware to the modules desired to build a system. Changes in any or all modules, when re-linked, create a new hardware allocation, avoiding the possibility of memory resource conflicts.

Code Composer Studio: IDE

Integrates: edit, code generation, and debug

Single-click access using buttons

Powerful graphing/profiling tools

Automated tasks using GEL scripts and CCS scripting

Built-in access to BIOS functions

Supports TI and 3rd party plug-ins



Projects Code Composer works with a project paradigm. Essentially, within CCS you create a project for each executable program you wish to create. Projects store all the information required to build the executable. For example, it lists things like: the source files, the header files, the target system’s memory-map, and program build options.

The CCS Project

List of files:Source (C, assembly)LibrariesDSP/BIOS configuration fileLinker command files

Project settings:Build options (compiler, Linker, assembler, and DSP/BIOS)Build configurations

Project (.pjt) files contain:

The project information is stored in a .PJT file, which is created and maintained by CCS. To create a new project, you need to select the Project:New… menu item.

Along with the main Project menu, you can also manage open projects using the right-click popup menu. Either of these menus allows you to Add Files… to a project. Of course, you can also drag-n-drop files onto the project from Windows Explorer.



Build Options Project options direct the code generation tools (i.e. compiler, assembler, linker) to create code according to your system’s needs. When you create a new project, CCS creates two sets of build options – called Configurations: one called Debug, the other Release (you might think of as Optimize).

To make it easier to choose build options, CCS provides a graphical user interface (GUI) for the various compiler options. Here’s a sample of the Debug configuration options.

Build Options GUI - Compiler

GUI has 8 pages of categories for code generation toolsControls many aspects of the build process, such as:

Optimization levelTarget deviceCompiler/assembly/link options

There is a one-to-one relationship between the items in the text box and the GUI check and drop-down box selections. Once you have mastered the various options, you can probably find yourself just typing in the options.



Build Options GUI - Linker

GUI has 3 categories for linking

Specify various link options

.\Debugmeans the directory called Debug one level below the .pjtfile directory$(Proj_dir)\Debugis an equivalent expression

There are many linker options but these four handle all of the basic needs. • -o <filename> specifies the output (executable) filename. • -m <filename> creates a map file. This file reports the linker’s results. • -c tells the compiler to autoinitialize your global and static variables.

• -x tells the compiler to exhaustively read the libraries. Without this option libraries are searched only once, and therefore backwards references may not be resolved.



Default Build Configurations

Add/Remove your own custom build configurations using Project ConfigurationsEdit a configuration:

1. Set it active2. Modify build options3. Save project

For new projects, CCS automatically creates two build configurations:

Debug (unoptimized)Release (optimized)

Use the drop-down menu to quickly select the build configuration

To help make sense of the many compiler options, TI provides two default sets of options (configurations) in each new project you create. The Release (optimized) configuration invokes the optimizer with –o3 and disables source-level, symbolic debugging by omitting –g (which disables some optimizations to enable debug).


Creating a Linker Command File


Sections Looking at a C program, you'll notice it contains both code and different kinds of data (global, local, etc.).

Sections

All code consists of different parts called sectionsAll default section names begin with “.”The compiler has default section names for initializedand uninitializedsections

int x = 2;

int y = 7;

void main(void)

{

long z;

z = x + y;

}

Global vars (.ebss) Init values (.cinit)

Local vars (.stack) Code (.text)

In the TI code-generation tools (as with any toolset based on the COFF – Common Object File Format), these various parts of a program are called Sections. Breaking the program code and data into various sections provides flexibility since it allows you to place code sections in ROM and variables in RAM. The preceding diagram illustrated four sections: • Global Variables • Initial Values for global variables • Local Variables (i.e. the stack) • Code (the actual instructions)



Following is a list of the sections that are created by the compiler. Along with their description, we provide the Section Name defined by the compiler.

Compiler Section Names

Name Description Link Location.text code FLASH.cinit initialization values for FLASH

global and static variables.econst constants (e.g. const int k = 3;) FLASH.switch tables for switch statements FLASH.pinit tables for global constructors (C++) FLASH

Initialized Sections

Name Description Link Location.ebss global and static variables RAM.stack stack space low 64Kw RAM.esysmem memory for far malloc functions RAM

Uninitialized Sections

Note: During development initialized sections could be linked to RAM since the emulator can be used to load the RAM

Sections of a C program must be located in different memories in your target system. This is the big advantage of creating the separate sections for code, constants, and variables. In this way, they can all be linked (located) into their proper memory locations in your target embedded system. Generally, they’re located as follows:

Program Code (.text)

Program code consists of the sequence of instructions used to manipulate data, initialize system settings, etc. Program code must be defined upon system reset (power turn-on). Due to this basic system constraint it is usually necessary to place program code into non-volatile memory, such as FLASH or EPROM.

Constants (.cinit – initialized data)

Initialized data are those data memory locations defined at reset.It contains constants or initial values for variables. Similar to program code, constant data is expected to be valid upon reset of the system. It is often found in FLASH or EPROM (non-volatile memory).

Variables (.ebss – uninitialized data)

Uninitialized data memory locations can be changed and manipulated by the program code during runtime execution. Unlike program code or constants, uninitialized data or variables must reside in volatile memory, such as RAM. These memories can be modified and updated, supporting the way variables are used in math formulas, high-level languages, etc. Each variable must be declared with a directive to reserve memory to contain its value. By their nature, no value is assigned, instead they are loaded at runtime by the program



Placing Sections in Memory

.ebss

.cinit

.text

MemoryM0SARAM

(0x400)0x00 0000

0x3E 8000

0x00 0400 M1SARAM(0x400)

FLASH(0x10000)

Sections

.stack

Linking code is a three step process:

1. Defining the various regions of memory (on-chip SARAM vs. FLASH vs. External Memory).

2. Describing what sections go into which memory regions

3. Running the linker with “build” or “rebuild”



Linker Command Files (.cmd) The linker concatenates each section from all input files, allocating memory to each section based on its length and location as specified by the MEMORY and SECTIONS commands in the linker command file.

Linking

Linker

Link.cmd

.map

.obj .out

Memory descriptionHow to place s/w into h/w

Memory-Map Description The MEMORY section describes the memory configuration of the target system to the linker.

The format is: Name: origin = 0x????, length = 0x????

For example, if you placed a 64Kw FLASH starting at memory location 0x3E8000, it would read:

MEMORY { FLASH: origin = 0x3E8000 , length = 0x010000 }

Each memory segment is defined using the above format. If you added M0SARAM and M1SARAM, it would look like:

MEMORY { M0SARAM: origin = 0x000000 , length = 0x0400 M1SARAM: origin = 0x000400 , length = 0x0400 }



Remember that the DSP has two memory maps: Program, and Data. Therefore, the MEMORY description must describe each of these separately. The loader uses the following syntax to delineate each of these:

Linker Page TI Definition

Page 0 Program

Page 1 Data

Linker Command FileMEMORY{ PAGE 0: /* Program Memory */FLASH: origin = 0x3E8000, length = 0x10000

PAGE 1: /* Data Memory */M0SARAM: origin = 0x000000, length = 0x400M1SARAM: origin = 0x000400, length = 0x400

}



Section Placement The SECTIONS section will specify how you want the sections to be distributed through memory. The following code is used to link the sections into the memory specified in the previous example:

SECTIONS { .text:> FLASH PAGE 0 .ebss:> M0SARAM PAGE 1 .cinit:> FLASH PAGE 0 .stack:> M1SARAM PAGE 1 }

The linker will gather all the code sections from all the files being linked together. Similarly, it will combine all ‘like’ sections.

Beginning with the first section listed, the linker will place it into the specified memory segment.

Linker Command FileMEMORY{ PAGE 0: /* Program Memory */FLASH: origin = 0x3E8000, length = 0x10000

PAGE 1: /* Data Memory */M0SARAM: origin = 0x000000, length = 0x400M1SARAM: origin = 0x000400, length = 0x400

}SECTIONS{

.text:> FLASH PAGE = 0

.ebss:> M0SARAM PAGE = 1

.cinit:> FLASH PAGE = 0

.stack:> M1SARAM PAGE = 1}


Exercise 2

Exercise 2 Looking at the following block diagram, and create a linker command file.

Exercise 2

Generic F28x device

M0SARAM(0x400)

M1SARAM(0x400)

L0SARAM(0x800)

0x00 0000 0x00 0400

0x00 8000 FLASH(0x10000)

0x3E 8000

Create the linker command file for the given memory map by filling in the blanks on the following slide

Fill in the blanks:

MEMORY{PAGE__: /* Program Memory */_____: origin = ____ ___, length = ___ _________: /* Data Memory */_______: origin = __ ____, length = ____________: origin = ____ ___, length = ____________: origin = ___ ____, length = __ __

}SECTIONS{

.text: > FLASH PAGE = 0

.ebss: > M0SARAM PAGE = 1

.cinit: > FLASH PAGE = 0

.stack: > M1SARAM PAGE = 1}

Exercise 2 - Command File


Exercise 2

Summary: Linker Command File The linker command file (.cmd) contains the inputs — commands — for the linker. This information is summarized below:

Linker Command File Summary

Memory Map DescriptionNameLocationSize

Sections DescriptionDirects software sections into named memory regionsAllows per-file discriminationAllows separate load/run locations


Lab 2: Linker Command File

Lab 2: Linker Command File Objective

Create a linker command file and link the C program file (Lab2.c) into the system described below.


System Description:• TMS320F28035• All internal RAM

blocks allocated

Placement of Sections:• .text into RAM Block L0SARAM on PAGE 0 (program memory)• .cinit into RAM Block L0SARAM on PAGE 0 (program memory)• .ebss into RAM Block M0SARAM on PAGE 1 (data memory)• .stack into RAM Block M1SARAM on PAGE 1 (data memory)

F28035

Memory

on-chip memory

0x00 8000 L0SARAM(0x800)

0x00 0400 M1SARAM(0x400)

0x00 8C00 L2DPSARAM(0x400)

0x00 8800 L1DPSARAM(0x400)

0x00 0000 M0SARAM(0x400)

0x00 9000 L3DPSARAM(0x1000)

System Description • TMS320F28035 • All internal RAM blocks allocated

Placement of Sections: • .text into RAM Block L0SARAM on PAGE 0 (program memory) • .cinit into RAM Block L0SARAM on PAGE 0 (program memory) • .ebss into RAM Block M0SARAM on PAGE 1 (data memory) • .stack into RAM Block M1SARAM on PAGE 1 (data memory)

Procedure

Create a New Project 1. Double click on the Code Composer Studio icon on the desktop. Maximize Code

Composer Studio to fill your screen. Code Composer Studio has a Connect/Disconnect feature which allows the target to be dynamically connected and disconnected. This will reset the JTAG link and also enable “hot swapping” a target board.



2. Connect to the target.

Click: Debug Connect

The menu bar (at the top) lists File ... Help. Note the horizontal tool bar below the menu bar and the vertical tool bar on the left-hand side. The window on the left is the project window and the large right-hand window is your workspace.

3. A project contains all the files you will need to develop an executable output file (.out) which can be run on the MCU hardware. Let’s create a new project for this lab. On the menu bar click:

Project New

type Lab2 in the project name field and make sure the save in location is: C:\C28x\Labs\Lab2, then click Finish. This will create a .pjt file which will invoke all the necessary tools (compiler, assembler, linker) to build your project. It will also create a debug folder that will hold immediate output files.

4. Add the C file to the new project. Click:

Project Add Files to Project…

and make sure you’re looking in C:\C28x\Labs\Lab2. Change the “files of type” to view C source files (*.c) and select Lab2.c and click OPEN. This will add the file Lab2.c to your newly created project.

5. Add Lab2.cmd to the project using the same procedure. This file will be edited during the lab exercise.

6. In the project window on the left, click the plus sign (+) to the left of Project. Now, click on the plus sign next to Lab2.pjt. Notice that the Lab2.cmd file is listed. Click on the plus sign next to Source to see the current source file list (i.e. Lab2.c).

Project Build Options 7. There are numerous build options in the project. The default option settings are sufficient

for getting started. We will inspect a couple of the default linker options at this time.

Click: Project Build Options…

8. Select the Linker tab. Notice that .out and .map files are being created. The .out file is the executable code that will be loaded into the MCU. The .map file will contain a linker report showing memory usage and section addresses in memory.

9. Set the Stack Size to 0x200.

10. Next, setup the compiler run-time support library. In the Libraries Category, find the Include Libraries (-l) box and enter: rts2800_ml.lib. Select OK and the Build Options window will close.

Edit the Linker Command File - Lab2a.cmd 11. To open and edit Lab2.cmd, double click on the filename in the project window.



12. Edit the Memory{} declaration by describing the system memory shown on the “Lab2: Linker Command File” slide in the objective section of this lab exercise. Place the L0SARAM and L3DPSARAM memory blocks into program memory on page 0. Place the other memory blocks into data memory on page 1.

13. In the Sections{} area, notice that a section called .reset has already been allocated. The .reset section is part of the rts2800_ml.lib, and is not needed. By putting the TYPE = DSECT modifier after its allocation, the linker will ignore this section and not allocate it.

14. Place the sections defined on the slide into the appropriate memories via the Sections{} area. Save your work and close the file.

Build and Load the Project 15. The top four buttons on the horizontal toolbar control code generation. Hover your

mouse over each button as you read the following descriptions:

Button Name Description

1 Compile File Compile, assemble the current open file 2 Incremental Build Compile, assemble only changed files, then link 3 Rebuild All Compile, assemble all files, then link 4 Stop Build Stop code generation

16. Code Composer Studio can automatically load the output file after a successful build. On the menu bar click: Option Customize… and select the “Program/Project/CIO” tab, then check “Load Program After Build”.

Also, Code Composer Studio can automatically connect to the target when started. Select the “Debug Properties” tab, check “Connect to the target at startup”, then click OK.

17. Click the “Build” button and watch the tools run in the build window. Check for errors (we have deliberately put an error in Lab2.c). When you get an error, scroll the build window at the bottom of the Code Composer Studio screen until you see the error message (in red), and simply double-click the error message. The editor will automatically open the source file containing the error, and position the mouse cursor at the correct code line.

18. Fix the error by adding a semicolon at the end of the "z = x + y" statement. For future knowlege, realize that a single code error can sometimes generate multiple error messages at build time. This was not the case here.

19. Rebuild the project (there should be no errors this time). The output file should automatically load. The Program Counter should be pointing to _c_int00 in the Disassembly Window.

20. Under Debug on the menu bar click “Go Main”. This will run through the C-environment initialization routine in the rts2800_ml.lib and stop at main() in Lab2.c.



Debug Enviroment Windows It is standard debug practice to watch local and global variables while debugging code. There are various methods for doing this in Code Composer Studio. We will examine two of them here: memory windows, and watch windows.

21. Open a memory window to view the global variable “z”.

Click: View Memory on the menu bar.

Type “&z” into the address field and then enter. Note that you must use the ampersand (meaning "address of") when using a symbol in a memory window address box. Also note that Code Composer Studio is case sensitive.

Set the properties format to “Hex 16 Bit – TI style” at the bottom of the window. This will give you more viewable data in the window. You can change the contents of any address in the memory window by double-clicking on its value. This is useful during debug.

22. Open the watch window to view the local variables x and y.

Click: View Watch Window on the menu bar.

Click the “Watch Locals” tab and notice that the local variables x and y are already present. The watch window will always contain the local variables for the code function currently being executed.

(Note that local variables actually live on the stack. You can also view local variables in a memory window by setting the address to “SP” after the code function has been entered).

23. We can also add global variables to the watch window if desired. Let's add the global variable “z”.

Click the “Watch 1” tab at the bottom of the watch window. In the empty box in the “Name” column, type “z” and then enter. An ampersand is not used here. The watch window knows you are specifying a symbol.

Check that the watch window and memory window both report the same value for “z”. Trying changing the value in one window, and notice that the value also changes in the other window.

Single-stepping the Code 24. Click the “Watch Locals” tab at the bottom of the watch window. Single-step through

main() by using the <F11> key (or you can use the Single Step button on the vertical toolbar). Check to see if the program is working as expected. What is the value for “z” when you get to the end of the program?

End of Exercise


Solutions

Solutions

MEMORY{PAGE 0: /* Program Memory */FLASH: origin = 0x3E8000, length = 0x10000PAGE 1: /* Data Memory */M0SARAM: origin = 0x000000, length = 0x400M1SARAM: origin = 0x000400, length = 0x400L0SARAM: origin = 0x008000, length = 0x800

}SECTIONS{

.text: > FLASH PAGE = 0


.cinit: > FLASH PAGE = 0

.stack: > M1SARAM PAGE = 1}

Exercise 2 - Solution

Lab 2: Solution - lab2.cmdMEMORY{

PAGE 0: /* Program Memory */L0SARAM: origin = 0x008000, length = 0x0800L3DPSARAM: origin = 0x009000, length = 0x1000PAGE 1: /* Data Memory */M0SARAM: origin = 0x000000, length = 0x0400M1SARAM: origin = 0x000400, length = 0x0400L1DPSARAM: origin = 0x008800, length = 0x0400L2DPSARAM: origin = 0x008C00, length = 0x0400

}

SECTIONS{

.text: > L0SARAM PAGE = 0


.cinit: > L0SARAM PAGE = 0

.stack: > M1SARAM PAGE = 1

.reset: > L0SARAM PAGE = 0, TYPE = DSECT}


Peripherial Registers Header Files

Introduction The purpose of the DSP2803x C-code header files is to simplify the programming of the many peripherals on the F28x device. Typically, to program a peripheral the programmer needs to write the appropriate values to the different fields within a control register. In its simplest form, the process consists of writing a hex value (or masking a bit field) to the correct address in memory. But, since this can be a burdensome and repetitive task, the C-code header files were created to make this a less complicated task.

The DSP2803x C-code header files are part of a library consisting of C functions, macros, peripheral structures, and variable definitions. Together, this set of files is known as the ‘header files.’

Registers and the bit-fields are represented by structures. C functions and macros are used to initialize or modify the structures (registers).

In this module, you will learn how to use the header files and C programs to facilitate programming the peripherals.


Understand the usage of the F2803x C-Code Header FilesBe able to program peripheral registersUnderstand how the structures are mapped with the linker command file

C2000 Piccolo Workshop - Peripheral Registers Header Files 3 - 1

Module Topics

Module Topics Peripherial Registers Header Files .......................................................................................................... 3-1

Module Topics......................................................................................................................................... 3-2 Traditional and Structure Approach to C Coding .................................................................................. 3-3 Naming Conventions............................................................................................................................... 3-6 F2803x C-Code Header Files ................................................................................................................. 3-7

Peripheral Structure .h File ................................................................................................................. 3-7 Global Variable Definitions File ........................................................................................................ 3-9 Mapping Structures to Memory.........................................................................................................3-10 Linker Command File........................................................................................................................3-10 Peripheral Specific Routines..............................................................................................................3-11

Summary ................................................................................................................................................3-12

3 - 2 C2000 Piccolo Workshop - Peripheral Registers Header Files

Traditional and Structure Approach to C Coding

Traditional and Structure Approach to C Coding Traditional Approach to C Coding

#define ADCCTL1 (volatile unsigned int *)0x00007100

...

void main(void)

{

*ADCCTL1 = 0x1234; //write entire register

*ADCCTL1 |= 0x4000; //enable ADC module

}

Disadvantages - Requires individual masks to be generated to manipulate individual bits

- Cannot easily display bit fields in Watch window- Will generate less efficient code in many cases

Advantages - Simple, fast and easy to type- Variable names exactly match register names (easy

to remember)

Structure Approach to C Codingvoid main(void)

{

AdcRegs.ADCCTL1.all = 0x1234; //write entire register

AdcRegs.ADCCTL1.bit.ADCENABLE = 1; //enable ADC module

}

Disadvantages - Can be difficult to remember the structure names(Editor Auto Complete feature to the rescue!)

- More to type (again, Editor Auto Complete featureto the rescue)

Advantages - Easy to manipulate individual bits.- Watch window is amazing! (next slide)- Generates most efficient code (on C28x)



The CCS Watch Window using #define

The CCS Watch Window using Structures



Is the Structure Approach Efficient?

You could not have coded this example any more efficiently with hand assembly!

The structure approach enables efficient compiler use of DP addressing mode and C28x atomic operations

C Source Code// Stop CPU Timer0CpuTimer0Regs.TCR.bit.TSS = 1;

// Load new 32-bit period valueCpuTimer0Regs.PRD.all = 0x00010000;

// Start CPU Timer0CpuTimer0Regs.TCR.bit.TSS = 0;

Generated Assembly Code*MOVW DP, #0030OR @4, #0x0010

MOVL XAR4, #0x010000MOVL @2, XAR4

AND @4, #0xFFEF

5 words, 5 cycles- Easy to read the code w/o comments- Bit mask built-in to structure

* C28x Compiler v5.0.1 with -g and either -o1, -o2, or -o3 optimization level

Compare with the #define ApproachThe #define approach relies heavily on less-efficient pointers for random memory access, and often does not take advantage of C28x atomic operations

C Source Code// Stop CPU Timer0*TIMER0TCR |= 0x0010;

// Load new 32-bit period value*TIMER0TPRD32 = 0x00010000;

// Start CPU Timer0*TIMER0TCR &= 0xFFEF;

Generated Assembly Code*MOV @AL,*(0:0x0C04)ORB AL, #0x10MOV *(0:0x0C04), @AL

MOVL XAR5, #0x010000MOVL XAR4, #0x000C0AMOVL *+XAR4[0], XAR5

MOV @AL, *(0:0x0C04)AND @AL, #0xFFEFMOV *(0:0x0C04), @AL

9 words, 9 cycles- Hard to read the code w/o comments- User had to determine the bit mask

* C28x Compiler v5.0.1 with -g and either -o1, -o2, or -o3 optimization level


Naming Conventions

Naming Conventions The header files use a familiar set of naming conventions. They are consistent with the Code Composer Studio configuration tool, and generated file naming conventions

Structure Naming Conventions

The DSP2803x header files define:All of the peripheral structuresAll of the register namesAll of the bit field namesAll of the register addresses

PeripheralName.RegisterName.all // Access full 16 or 32-bit register

PeripheralName.RegisterName.half.LSW // Access low 16-bits of 32-bit register

PeripheralName.RegisterName.half.MSW // Access high 16-bits of 32-bit register

PeripheralName.RegisterName.bit.FieldName // Access specified bit fields of register

Notes: [1] “PeripheralName” are assigned by TI and found in the DSP2803x header files. They are a combination of capital and small letters (i.e. CpuTimer0Regs).

[2] “RegisterName” are the same names as used in the data sheet. They are always in capital letters (i.e. TCR, TIM, TPR,..).

[3] “FieldName” are the same names as used in the data sheet.They are always in capital letters (i.e. POL, TOG, TSS,..).

Editor Auto Complete to the Rescue!


F2803x C-Code Header Files

F2803x C-Code Header Files The C-code header files consists of .h, c source files, linker command files, and other useful example programs, documentations and add-ins for Code Composer Studio.

DSP2803x Header File Package(http://www.ti.com, literature # SPRC892)

Contains everything needed to use the structure approachDefines all peripheral register bits and register addressesHeader file package includes:

\DSP2803x_headers\include .h files\DSP2803x_headers\cmd linker .cmd files\DSP2803x_headers\gel .gel files for CCS\DSP2803x_examples CCS3 examples\DSP2803x_examples_ccsv4 CCS4 examples\doc documentation

A peripheral is programmed by writing values to a set of registers. Sometimes, individual fields are written to as bits, or as bytes, or as entire words. Unions are used to overlap memory (register) so the contents can be accessed in different ways. The header files group all the registers belonging to a specific peripheral.

A DSP2803x_Peripheral.gel GEL file can provide a pull down menu to load peripheral data structures into a watch window. Code Composer Studio can load a GEL file automatically. To include fuctions to the standard F28035.gel that is part of Code Composer Studio, add:

GEL_LoadGel(“base_path/gel/DSP2803x_Peripheral.gel”)

The GEL file can also be loaded during a Code Composer Studio session by clicking:

File Load GEL…

Peripheral Structure .h FileThe DSP2803x_Device.h header file is the main include file. By including this file in the .c source code, all of the peripheral specific .h header files are automatically included. Of course, each specific .h header file can be included individually in an application that does not use all the header files, or you can comment out the ones you do not need. (Also includes typedef statements).



Peripheral Structure .h files (1 of 2)

DSP2803x_Adc.h

#include "DSP2803x_Device.h"

Void InitAdc(void){

/* Reset the ADC module */AdcRegs.ADCCTL1.bit.RESET = 1;

/* configure the ADC register */AdcRegs.ADCCTL1.all = 0x00E4;

};

Your C-source file (e.g., Adc.c)

Contain bits field structure definitions for each peripheral register

// ADC Individual Register Bit Definitions:struct ADCCTL1_BITS { // bits description

Uint16 TEMPCONV:1; // 0 Temperature sensor connectionUint16 VREFLOCONV:1; // 1 VSSA connectionUint16 INTPULSEPOS:1; // 2 INT pulse generation controlUint16 ADCREFSEL:1; // 3 Internal/external reference selectUint16 rsvd1:1; // 4 reservedUint16 ADCREFPWD:1; // 5 Reference buffers powerdownUint16 ADCBGPWD:1; // 6 ADC bandgap powerdownUint16 ADCPWDN:1; // 7 ADC powerdownUint16 ADCBSYCHN:5; // 12:8 ADC busy on a channelUint16 ADCBSY:1; // 13 ADC busy signalUint16 ADCENABLE:1; // 14 ADC enableUint16 RESET:1; // 15 ADC master reset

};// Allow access to the bit fields or entire register:union ADCCTL1_REG {

Uint16 all;struct ADCCTL1_BITS bit;

};// ADC External References & Function Declarations:extern volatile struct ADC_REGS AdcRegs;

Peripheral Structure .h files (2 of 2)

The header file package contains a .h file for each peripheral in the device

DSP2803x_Device.hMain include fileWill include all other .h filesInclude this file (directly or indirectly) in each source file:

#include “DSP2803x_Device.h”

DSP2803x_Adc.h DSP2803x_BootVars.h DSP2803x_Cla.hDSP2803x_Comp.h DSP2803x_CpuTimers.h DSP2803x_DevEmu.hDSP2803x_Device.h DSP2803x_ECan.h DSP2803x_ECap.hDSP2803x_EPwm.h DSP2803x_EQep.h DSP2803x_Gpio.hDSP2803x_I2c.h DSP2803x_Lin.h DSP2803x_NmiIntrupt.hDSP2803x_PieCtrl.h DSP2803x_PieVect.h DSP2803x_Sci.hDSP2803x_Spi.h DSP2803x_SysCtrl.h DSP2803x_XIntrupt.h



Global Variable Definitions File With DSP2803x_GlobalVariableDefs.c included in the project all the needed variable definitions are globally defined.

Global Variable Definitions FileDSP2803x_GlobalVariableDefs.c

Declares a global instantiation of the structure for each peripheralEach structure is placed in its own section using a DATA_SECTION pragma to allow linking to the correct memory (see next slide)

Add this file to your CCS project:DSP2803x_GlobalVariableDefs.c

#include "DSP2803x_Device.h"…#pragma DATA_SECTION(AdcRegs,"AdcRegsFile");volatile struct ADC_REGS AdcRegs;…

DSP2803x_GlobalVariableDefs.c



Mapping Structures to Memory The data structures describe the register set in detail. And, each instance of the data type (i.e., register set) is unique. Each structure is associated with an address in memory. This is done by (1) creating a new section name via a DATA_SECTION pragma, and (2) linking the new section name to a specific memory in the linker command file.

Linker Command Files for the StructuresDSP2803x_nonBIOS.cmd and DSP2803x_BIOS.cmd

Links each structure to the address of the peripheral using the structures named section

non-BIOS and BIOS versions of the .cmd file

Add one of these files to your CCS project:DSP2803x_nonBIOS.cmd

orDSP2803x_BIOS.cmd

MEMORY {

PAGE1:...ADC: origin=0x007100, length=0x000080...

}

SECTIONS{

...AdcRegsFile: > ADC PAGE = 1...

}

DSP2803x_Headers_nonBIOS.cmd

#include "DSP2803x_Device.h"…#pragma DATA_SECTION(AdcRegs,"AdcRegsFile");volatile struct ADC_REGS AdcRegs;…

DSP2803x_GlobalVariableDefs.c

Linker Command File When using the header files, the user adds the MEMORY regions that correspond to the CODE_SECTION and DATA_SECTION pragmas found in the .h and global-definitons.c file.

The user can modify their own linker command file, or use a pre-configured linker command file such as F28035.cmd. This file has the peripheral memory regions defined and tied to the individual peripheral.



Peripheral Specific Routines Peripheral Specific C functions are used to initialize the peripherals. They are used by adding the appropriate .c file to the project.

Peripheral Specific Examples

Example projects for each peripheralHelpful to get you started


Summary

Summary Peripheral Register Header Files

SummaryEasier code developmentEasy to useGenerates most efficient codeIncreases effectiveness of CCS watch windowTI has already done all the work!

Use the correct header file package for your device:F2803x # SPRC892F2802x # SPRC832F2833x and F2823x # SPRC530F280x and F2801x # SPRC191F2804x # SPRC324F281x # SPRC097

Go to http://www.ti.com and enter the literature number in the keyword search box


Reset and Interrupts

Introduction This module describes the interrupt process and explains how the Peripheral Interrupt Expansion (PIE) works.


Describe the C28x reset processList the event sequence during an interruptDescribe the C28x interrupt structure

C2000 Piccolo Workshop - Reset and Interrupts 4 - 1

Module Topics

Module Topics Reset and Interrupts ................................................................................................................................. 4-1

Module Topics......................................................................................................................................... 4-2 Reset........................................................................................................................................................ 4-3

Reset - Bootloader .............................................................................................................................. 4-3 Emulation Boot Mode ........................................................................................................................ 4-4 Stand-Alone Boot Mode..................................................................................................................... 4-4 Reset Code Flow – Summary ............................................................................................................. 4-5

Interrupts ................................................................................................................................................ 4-6 Interrupt Processing............................................................................................................................ 4-6 Interrupt Flag Register (IFR) .............................................................................................................. 4-7 Interrupt Enable Register (IER).......................................................................................................... 4-7 Interrupt Global Mask Bit (INTM)..................................................................................................... 4-8 Peripheral Interrupt Expansion (PIE) ................................................................................................. 4-8 PIE Interrupt Vector Table ................................................................................................................4-10 Interrupt Response and Latency ........................................................................................................4-11

4 - 2 C2000 Piccolo Workshop - Reset and Interrupts

Reset

Reset Reset Sources

POR – Power-On Rest generates a device reset during power-up conditionsBOR – Brown-Out Reset generates a device reset if the power supply drops below specification for the device

Note: Devices support an on-chip regulator (VREG) to generate the core voltage

Watchdog Timer

XRS pin activeTo XRS pin

C28x core

XRSPower-on Reset

Brown-out Reset

Missing Clock Detect

Logic shown is functional representation, not actual implementation

Reset - Bootloader

Reset – Bootloader

TRST = JTAG Test Reset EMU_KEY & EMU_BMODE located in PIE at 0x0D00 & 0x0D01, respectivelyOPT_KEY & OTP_BMODE located in OTP at 0x3D78FE & 0x3D78FF, respectively

Reset vector fetched from

boot ROM0x3F FFC0

Bootloader setsOBJMODE = 1

AMODE = 0



Stand-alone BootBoot determined by

2 GPIO pins and2 OTP locations:

OTP_KEY and OTP_BMODE

TRST = 1 TRST = 0

ResetOBJMODE = 0

AMODE = 0ENPIE = 0INTM = 1

YES NOEmulator Connected ?


Reset

Emulation Boot Mode

Emulation Boot Mode (TRST = 1)

If either EMU_KEY or EMU_BMODE are invalid, the “wait” boot mode is used. These values can then be modified using the debugger and a reset issued to restart the boot process



Emulator Connected

EMU_KEY = 0x55AA ? Boot ModeWait

Boot ModeParallel I/OSCIWaitGetModeSPII2COTPCANM0 SARAMFLASHWait

EMU_BMODE =0x00000x00010x00020x00030x00040x00050x00060x00070x000A0x000Bother

Boot ModeFLASH

Boot ModeSCIFLASHSPII2COTPCANFLASH

OTP_BMODE =0x00010x00030x00040x00050x00060x0007other

NO

NO

YES

YES

OTP_KEY = 0x55AA ?

Stand-Alone Boot Mode

Stand-Alone Boot Mode (TRST = 0)

Stand-alone BootBoot determined by

2 GPIO pins and2 OTP locations:

OTP_KEY and OTP_BMODE

Emulator Not Connected

Boot ModeParallel I/OSCIWaitGetMode

GPIO GPIO37 340 00 11 01 1

Boot ModeFLASH

Boot ModeSCIFLASHSPII2COTPCANFLASH

OTP_BMODE =0x00010x00030x00040x00050x00060x0007other

NO

YES

Note that the boot behavior for unprogrammed OTP is the “FLASH” boot mode

OTP_KEY = 0x55AA ?


Reset

Reset Code Flow – Summary

Reset Code Flow - Summary

M0 SARAM (1Kw)

FLASH (64Kw)0x3F7FF6

0x3D7800

0x3E8000

0x000000

0x3FE000

0x3FFFC0

Boot ROM (8Kw)

BROM vector (64w)0x3FF7BB

Boot Code

••

••

RESET

Execution Entrydetermined by

Emulation Boot Mode orStand-Alone Boot Mode

BootloadingRoutines

(SCI, SPI, I2C, Parallel I/O)

0x3FF7BB

0x000000

OTP (1Kw)0x3D7800


Interrupts

Interrupts Interrupt Sources

ePWM, eCAP, eQEP, ADC, SCI, SPI, I2C, eCAN,LIN, CLA, WD

Internal Sources

External Sources

XINT1 – XINT3

TZx

XRS

NMI

C28x CORE

INT1

INT13

INT2INT3

INT12

INT14

XRS

•••

PIE (Peripheral

InterruptExpansion)

TINT2TINT1TINT0

Interrupt Processing

A valid signal on a specific interrupt line causes the latch to display a “1” in the appropriate bit

Maskable Interrupt ProcessingConceptual Core Overview

1

0

1

(IFR)“Latch”

INT1

INT2

INT14

CoreInterrupt

C28xCore

(INTM)“Global Switch”

(IER)“Switch”

If the individual and global switches are turned “on” the interrupt reaches the core


Interrupts

Interrupt Flag Register (IFR)

Interrupt Flag Register (IFR)

RTOSINT DLOGINT INT14 INT13 INT12 INT11 INT10 INT989101112131415

INT8 INT7 INT6 INT5 INT4 INT3 INT2 INT101234567

Pending : IFR Bit = 1Absent : IFR Bit = 0

Compiler generates atomic instructions (non-interruptible) for setting/clearing IFRIf interrupt occurs when writing IFR, interrupt has priorityIFR(bit) cleared when interrupt is acknowledged by CPURegister cleared on reset

/*** Manual setting/clearing IFR ***/extern cregister volatile unsigned int IFR;

IFR |= 0x0008; //set INT4 in IFRIFR &= 0xFFF7; //clear INT4 in IFR

Interrupt Enable Register (IER)

Interrupt Enable Register (IER)

RTOSINT DLOGINT INT14 INT13 INT12 INT11 INT10 INT989101112131415

INT8 INT7 INT6 INT5 INT4 INT3 INT2 INT101234567

Enable: Set IER Bit = 1Disable: Clear IER Bit = 0

Compiler generates atomic instructions (non-interruptible) for setting/clearing IERRegister cleared on reset

/*** Interrupt Enable Register ***/extern cregister volatile unsigned int IER;

IER |= 0x0008; //enable INT4 in IERIER &= 0xFFF7; //disable INT4 in IER


Interrupts

Interrupt Global Mask Bit (INTM)

Interrupt Global Mask Bit

INTM used to globally enable/disable interrupts:Enable: INTM = 0Disable: INTM = 1 (reset value)

INTM modified from assembly code only:

INTMST1Bit 0

/*** Global Interrupts ***/asm(“ CLRC INTM”); //enable global interruptsasm(“ SETC INTM”); //disable global interrupts

Peripheral Interrupt Expansion (PIE)

Peripheral Interrupt Expansion - PIE

Peri

pher

al In

terr

upts

12

x8 =

96

IFR

IER

INTM 28x

Core

28x Core Interrupt logic

PIE module for 96 Interrupts

INT1.x interrupt groupINT2.x interrupt groupINT3.x interrupt groupINT4.x interrupt groupINT5.x interrupt groupINT6.x interrupt groupINT7.x interrupt groupINT8.x interrupt groupINT9.x interrupt groupINT10.x interrupt groupINT11.x interrupt groupINT12.x interrupt group

INT1 – INT12

12 Interrupts

96

INT1.1

INT1.2

INT1.8

1

0

1

•••

•••

INT1

PIEIFR1 PIEIER1Interrupt Group 1

(TINT1)(TINT2)


Interrupts

F2803x PIE Interrupt Assignment TableINTx.8 INTx.7 INTx.6 INTx.5 INTx.4 INTx.3 INTx.2 INTx.1

INT1 WAKEINT TINT0 ADCINT9 XINT2 XINT1 ADCINT2 ADCINT1

INT2 EPWM7_TZINT

EPWM6_TZINT

EPWM5_TZINT

EPWM4_TZINT

EPWM3_TZINT

EPWM2_TZINT

EPWM1_TZINT

INT3 EPWM7_INT

EPWM6_INT

EPWM5_INT

EPWM4_INT

EPWM3_INT

EPWM2_INT

EPWM1_INT

INT4 ECAP1_INT

INT5 EQEP1_INT

INT6 SPITXINTB

SPIRXINTB

SPITXINTA

SPIRXINTA

INT7

INT8 I2CINT2A I2CINT1A

INT9 LIN1INTA

LIN0INTA

SCITXINTA

SCIRXINTA

INT10 ADCINT8 ADCINT7 ADCINT6 ADCINT5 ADCINT4 ADCINT3 ADCINT2 ADCINT1

INT11 CLA1_INT8

CLA1_INT7

CLA1_INT6

CLA1_INT5

CLA1_INT4

CLA1_INT3

CLA1_INT2

CLA1_INT1

INT12 LUF LVF XINT3

ECAN0INTA

ECAN1INTA

PIE Registers

INTx.2INTx.3INTx.4INTx.5INTx.6INTx.7INTx.8 INTx.10123456715 - 8

reserved

PIEIFRx register (x = 1 to 12)

INTx.2INTx.3INTx.4INTx.5INTx.6INTx.7INTx.8 INTx.10123456715 - 8

reserved

PIEIERx register (x = 1 to 12)

reserved PIEACKx

PIE Interrupt Acknowledge Register (PIEACK)124 356789 0101115 - 12

ENPIEPIEVECT

PIECTRL register 015 - 1

#include “DSP2803x_Device.h”PieCtrlRegs.PIEIFR1.bit.INTx4 = 1; //manually set IFR for XINT1 in PIE group 1PieCtrlRegs.PIEIER3.bit.INTx2 = 1; //enable EPWM2_INT in PIE group 3PieCtrlRegs.PIEACK.all = 0x0004; //acknowledge the PIE group 3PieCtrlRegs.PIECTRL.bit.ENPIE = 1; //enable the PIE


Interrupts

PIE Interrupt Vector Table

Vector Offset

Default Interrupt Vector Table at Reset

Memory0

BROM Vectors64w

ENPIE = 0

0x3F FFC0

0x3F FFFF

PIE Vectors256w

0x00 0D00

DATALOGRTOSINTEMUINTNMI

020406080A0C0E10121416181A1C1E2022242628-3E

ILLEGALUSER 1-12

INT1INT2INT3INT4INT5INT6INT7INT8INT9INT10INT11INT12INT13INT14

RESET 00 Default Vector TableRe-mapped when

ENPIE = 1

PieVectTableInit{ }Used to initialize PIE vectors

PIE Vector Mapping (ENPIE = 1)

PIE vector location – 0x00 0D00 – 256 words in data memory RESET and INT1-INT12 vector locations are re-mappedCPU vectors are re-mapped to 0x00 0D00 in data memory

PIE INT12.8 Interrupt Vector0x00 0DFEINT12.8………PIE INT12.1 Interrupt Vector0x00 0DF0INT12.1………PIE INT1.8 Interrupt Vector0x00 0D4EINT1.8………PIE INT1.1 Interrupt Vector0x00 0D40INT1.1User Defined Trap0x00 0D3EUSER12………CPU Data Logging Interrupt0x00 0D1EDATALOGCPU Timer 20x00 0D1CINT14CPU Timer 10x00 0D1AINT13INT12 remapped to PIE group below0x00 0D18INT12INTx remapped to PIE group below……INT1 remapped to PIE group below0x00 0D02INT1Reset fetched from Boot ROM 0x3F FFC00x00 0D00ResetPIE Vector DescriptionPIE AddressVector Name

Rem

appe

d


Interrupts

Device Vector Mapping - Summary

_c_int00:. . .

CALL main()

main(){ initialization();

. . .}

Initialization(){Load PIE VectorsEnable the PIEEnable PIEIEREnable Core IEREnable INTM

}

PIE Vector Table256 Word RAM

0x00 0D00 – 0DFF

RESET<0x3F FFC0>

Reset Vector <0x3F F7BB> = Boot Code Flash Entry Point <0x3F 7FF6 > = LB _c_int00User Code Start < _c_int00 >

Interrupt Response and Latency

Interrupt Response - Hardware Sequence

Note: some actions occur simultaneously, none are interruptible

CPU Action Description

T ST0AH ALPH PLAR1 AR0DP ST1DBSTAT IERPC(msw) PC(lsw)

Registers → stack 14 Register words auto saved0 → IFR (bit) Clear corresponding IFR bit0 → IER (bit) Clear corresponding IER bit1 → INTM/DBGM Disable global ints/debug eventsVector → PC Loads PC with int vector addressClear other status bits Clear LOOP, EALLOW, IDLESTAT


Interrupts

Interrupt Latency

Latency

Depends on wait states, INTM, etc.Maximum latency:

Recognition delay (3), SP alignment (1),

interrupt placed in pipeline

4

Minimum latency (to when real work occurs in the ISR): Internal interrupts: 14 cycles

External interrupts: 16 cycles

Get vector and place

in PC (3 reg. pairs

saved)

3F1/F2/D1 of

ISR instruction

(3 reg. pairs saved)

3Save return

address

1D2/R1/R2 of

ISR instruction

3Sync ext.

signal(ext.

interrupt only)

2cycles

Assumes ISR in internal RAM

Internal interrupt occurs here

ext. interrupt occurs here

ISR instruction executed on next cycle


System Initialization

Introduction This module discusses the operation of the OSC/PLL-based clock module and watchdog timer. Also, the general-purpose digital I/O ports, external interrups, various low power modes and the EALLOW protected registers will be covered.


OSC/PLL Clock Module

Watchdog Timer

General Purpose Digital I/O

External Interrupts

Low Power Modes

Register Protection

C2000 Piccolo Workshop - System Initialization 5 - 1

Module Topics

Module Topics System Initialization.................................................................................................................................. 5-1

Module Topics......................................................................................................................................... 5-2 Oscillator/PLL Clock Module................................................................................................................. 5-3 Watchdog Timer...................................................................................................................................... 5-6 General-Purpose Digital I/O .................................................................................................................5-10 External Interrupts.................................................................................................................................5-13 Low Power Modes..................................................................................................................................5-14 Register Protection ................................................................................................................................5-16 Lab 5: System Initialization ...................................................................................................................5-18

5 - 2 C2000 Piccolo Workshop - System Initialization

Oscillator/PLL Clock Module

Oscillator/PLL Clock Module F2803x Oscillator / PLL Clock Module

(lab file: SysCtrl.c)

XCLKINOFF

X2 XTAL

OSC

X1

XTAL

0*10

XCLKIN

InternalOSC 1

(10 MHz)

InternalOSC 2

(10 MHz)

OSCCLKSRC2

0*1

WDCLKSRCSEL

0*1

OSCCLKSRCSEL

0*1

10110100* CPU

Timer 2SYSCLKOUT

TMR2CLKSRCSEL

PLL VCOCLK

OSCCLK

C28xCore

CLKIN

SYSCLKOUT

LOSPCP

LSPCLK

(PLL bypass)

LSPCLK

DIV

SCI, SPIAll other peripherals

clocked by SYSCLKOUT

MU

X

1/n

DIVSEL

OSC1CLK

OSC2CLK

EXTCLK

WatchdogModule

WDCLK

CPUTMR2CLK

* = default

The on-chip oscillator and phase-locked loop (PLL) block provide all the necessary clocking signals for the F2803x devices. The two internal oscillators (INTOSC1 and INTOSC2) need no external components.

F2803x PLL and LOSPCP(lab file: SysCtrl.c)

DIV CLKIN0 0 0 0 OSCCLK / n * (PLL bypass)0 0 0 1 OSCCLK x 1 / n0 0 1 0 OSCCLK x 2 / n0 0 1 1 OSCCLK x 3 / n0 1 0 0 OSCCLK x 4 / n0 1 0 1 OSCCLK x 5 / n0 1 1 0 OSCCLK x 6 / n0 1 1 1 OSCCLK x 7 / n1 0 0 0 OSCCLK x 8 / n1 0 0 1 OSCCLK x 9 / n1 0 1 0 OSCCLK x 10 / n1 0 1 1 OSCCLK x 11 / n1 1 0 0 OSCCLK x 12 / n

Input Clock Fail Detect CircuitryPLL will issue a “limp mode” clock (1-4 MHz) if input clock is removed after PLL has locked. An internal device reset will also be issued (XRSnpin not driven).

DIVSEL n

0x /4 *10 /211 /1

* defaultNote: /1 mode can only be used when PLL is bypassed

LSPCLK Peripheral Clk Freq0 0 0 SYSCLKOUT / 10 0 1 SYSCLKOUT / 20 1 0 SYSCLKOUT / 4 *0 1 1 SYSCLKOUT / 61 0 0 SYSCLKOUT / 81 0 1 SYSCLKOUT / 101 1 0 SYSCLKOUT / 121 1 1 SYSCLKOUT / 14

PLL VCOCLK

OSCCLK

C28xCore

CLKIN SYSCLKOUT

LOSPCP

(PLL bypass)

LSPCLKMUX 1/n

SysCtrlRegs.PLLCR.bit.DIV

SysCtrlRegs.PLLSTS.bit.DIVSEL

SysCtrlRegs.LOSPCP.bit.LSPCLK



The PLL has a 4-bit ratio control to select different CPU clock rates. In addition to the on-chip oscillators, two external modes of operation are supported – crystal operation, and external clock source operation. Crystal operation allows the use of an external crystal/resonator to provide the time base to the device. External clock source operation allows the internal (crystal) oscillator to be bypassed, and the device clocks are generated from an external clock source input on the XCLKIN pin. The C28x core provides a SYSCLKOUT clock signal. This signal is prescaled to provide a clock source for some of the on-chip communication peripherals through the low-speed peripheral clock prescaler. Other peripherals are clocked by SYSCLKOUT and use their own clock prescalers for operation.

Clock Control Register(lab file: SysCtrl.c)

15 14 13 11 10 9 812NMIRESET

SELXTAL

OSCOFFINTOSC2

HALTIINTOSC2

OFFINTOSC1

HALTIINTOSC1

OFFWDHALTIXCLKINOFF

Upper Register:

InternalOscillator 1 Off0 = on1 = off

Internal Oscillator 1HALT Mode Ignore0 = automatic turn on/off 1 = ignores HALT Mode

InternalOscillator 2 Off0 = on1 = off

Internal Oscillator 2HALT Mode Ignore0 = automatic turn on/off 1 = ignores HALT Mode

WatchdogHALT Mode Ignore0 = automatic turn on/off 1 = ignores HALT Mode

XCLKINOff0 = on1 = off

CrystalOscillatorOff0 = on1 = off

NMIReset0 = no delay1 = delay

0 = default



Clock Control Register(lab file: SysCtrl.c)

7 - 5 4 - 3 2 1 0

TMR2CLKSRCSEL WDCLKSRCSEL

OSCCLKSRC2SEL

OSCCLKSRCSELTMR2CLKPRESCALE

OscillatorClock Source0 = internal OSC11 = external or

internal OSC2

Oscillator 2Clock Source0 = external1 = internal OSC2

Lower Register:

WatchdogClock Source0 = internal OSC11 = external or

internal OSC2

CPU Timer 2Clock Source00 = SYSCLKOUT01 = external10 = internal OSC111 = internal OSC2

CPU Timer 2Clock Prescale000 = /1001 = /2010 = /4011 = /8100 = /161xx = reserved 0 = default

The peripheral clock control register allows individual peripheral clock signals to be enabled or disabled. If a peripheral is not being used, its clock signal could be disabled, thus reducing power consumption.

Peripheral Clock Control Registers(lab file: SysCtrl.c)

15 14 13 11 10 9 812

7 6 5 4 3 2 1 0

SysCtrlRegs.PCLKCR0

SysCtrlRegs.PCLKCR1

SysCtrlRegs.PCLKCR3

15 14 13 11 10 9 812

7 6 5 4 3 2 1 0

ECANAENCLK

SCIAENCLK

SPIAENCLK

I2CAENCLK

ADCENCLK

TBCLKSYNC

EQEP1ENCLK

ECAP1ENCLK

EPWM6ENCLK

EPWM5ENCLK

EPWM4ENCLK

EPWM3ENCLK

EPWM2ENCLK

EPWM1ENCLK

reservedreserved

reserved

Module Enable Clock Bit0 = disable (default) 1 = enable

HRPWMENCLK

15 14 13 11 10 9 812CPUTIMER2

ENCLKCPUTIMER1

ENCLKCPUTIMER0

ENCLKGPIOINENCLKreserved reserved reserved

7 6 5 4 3 2 1 0

reserved reserved reserved reserved reserved COMP1ENCLK

COMP2ENCLK

EPWM7ENCLK

COMP3ENCLK

SPIAENCLKreserved reserved reserved reserved

LINAENCLKreserved

reserved reserved reserved reserved reserved reserved

CLA1ENCLK


Watchdog Timer

Watchdog Timer Watchdog Timer

Resets the C28x if the CPU crashesWatchdog counter runs independent of CPUIf counter overflows, a reset or interrupt is triggered (user selectable)CPU must write correct data key sequence to reset the counter before overflow

Watchdog must be serviced or disabled within 131,072 WDCLK cycles after resetThis translates to 13.11 ms with a 10 MHz WDCLK

The watchdog timer provides a safeguard against CPU crashes by automatically initiating a reset if it is not serviced by the CPU at regular intervals. In motor control applications, this helps protect the motor and drive electronics when control is lost due to a CPU lockup. Any CPU reset will revert the PWM outputs to a high-impedance state, which should turn off the power converters in a properly designed system.

The watchdog timer is running immediately after system power-up/reset, and must be dealt with by software soon after. Specifically, you have 13.11 ms (for a 60 MHz device) after any reset before a watchdog initiated reset will occur. This translates into 131,072 WDCLK cycles, which is a seemingly tremendous amount! Indeed, this is plenty of time to get the watchdog configured as desired and serviced. A failure of your software to properly handle the watchdog after reset could cause an endless cycle of watchdog initiated resets to occur.


Watchdog Timer

Watchdog Timer Module (lab file: Watchdog.c)

WDCLK

SystemReset

8-bit WatchdogCounter

CLR

WatchdogReset KeyRegister

55 + AADetector

1 0 1//3

3

WDDIS

WDCHK 2-0

Bad WDCHK Key

/512

OutputPulse

WDRST

WDINT

WDOVERRIDE

Good Key

WatchdogPrescaler

WDPS

WDPS FRC WD timeout periodBits rollover @ 10 MHz WDCLK

00x: 1 13.11 ms *010: 2 26.22 ms011: 4 52.44 ms100: 8 104.88 ms101: 16 209.76 ms110: 32 419.52 ms111: 64 839.04 ms

Watchdog Period Selection

Remember: Watchdog starts counting immediately after reset is released!Reset default with WDCLK = 10 MHz computed as

(1/10 MHz) * 512 * 256 = 13.11 ms

* reset default


Watchdog Timer

Watchdog Timer Control RegisterSysCtrlRegs.WDCR (lab file: Watchdog.c)

WDFLAG WDDIS

7 6 5 - 3 2 - 0

WDPSWDCHK

Logic Check BitsWrite as 101 or reset immediately triggered

WD PrescaleSelection Bits

Watchdog Disable BitWrite 1 to disable

(Functions only if WD OVERRIDEbit in SCSR is equal to 1)

reserved

15 - 8

WD Flag BitGets set when the WD causes a reset

• Writing a 1 clears this bit• Writing a 0 has no effect

WDPS WDCLK =0 0 0 OSCCLK / 512 / 10 0 1 OSCCLK / 512 / 10 1 0 OSCCLK / 512 / 20 1 1 OSCCLK / 512 / 41 0 0 OSCCLK / 512 / 81 0 1 OSCCLK / 512 / 161 1 0 OSCCLK / 512 / 321 1 1 OSCCLK / 512 / 64

Resetting the WatchdogSysCtrlRegs.WDKEY (lab file: Watchdog.c)

WDKEY write values:55h - counter enabled for reset on next AAh writeAAh - counter set to zero if reset enabled

Writing any other value has no effectWatchdog should not be serviced solely in an ISR

If main code crashes, but interrupt continues to execute, the watchdog will not catch the crashCould put the 55h WDKEY in the main code, and the AAh WDKEY in an ISR; this catches main code crashes and also ISR crashes

reserved7 - 015 - 8

WDKEY


Watchdog Timer

WDKEY Write Results

SequentialStep

123456789

1011121314

Value Writtento WDKEY

AAhAAh55h55h55hAAhAAh55hAAh55h23hAAh55hAAh

Result

No actionNo actionWD counter enabled for reset on next AAh writeWD counter enabled for reset on next AAh writeWD counter enabled for reset on next AAh writeWD counter is resetNo actionWD counter enabled for reset on next AAh writeWD counter is resetWD counter enabled for reset on next AAh writeNo effect; WD counter not reset on next AAh writeNo action due to previous invalid valueWD counter enabled for reset on next AAh writeWD counter is reset

System Control and Status RegisterSysCtrlRegs.SCSR (lab file: Watchdog.c)

WD Override (protect bit)Protects WD from being disabled

0 = WDDIS bit in WDCR has no effect (WD cannot be disabled)1 = WDDIS bit in WDCR can disable the watchdog

• This bit is a clear-only bit (write 1 to clear)• The reset default of this bit is a 1

01215 - 3

WDOVERRIDEWDENINTWDINTSreserved

WD Enable InterruptWD Interrupt Status(read only)

0 = active1 = not active

0 = WD generates a DSP reset1 = WD generates a WDINT interrupt


General-Purpose Digital I/O

General-Purpose Digital I/O F2803x GPIO Grouping Overview

(lab file: Gpio.c)

GPIO Port A Mux1Register (GPAMUX1)

[GPIO 0 to 15] GPIO Port ADirection Register

(GPADIR)[GPIO 0 to 31]

GPIO

Port AG

PIO P

ort B

Internal Bus

GPIO Port A Mux2Register (GPAMUX2)

[GPIO 16 to 31]

GPIO Port B Mux1Register (GPBMUX1)

[GPIO 32 to 44]

GPIO Port BDirection Register

(GPBDIR)[GPIO 32 to 44]

ANA

LOG

Port

ANALOG I/O Mux1Register (AIOMUX1)

[AIO 0 to 15]

ANALOG PortDirection Register

(AIODIR)[AIO 0 to 15]

InputQual

InputQual

•

F2803x GPIO Pin Block Diagram(lab file: Gpio.c)

• •01

00MUX Control Bits *00 = GPIO01 = Peripheral 110 = Peripheral 211 = Peripheral 3

Peripheral1

I/O DATBit (R/W) In

Out

I/O DIR Bit0 = Input1 = Output

GPxMUX1GPxMUX2

GPxDIR

GPxDAT

GPxSETGPxCLEAR

GPxTOGGLE

•• 10

11

Peripheral2

Peripheral3

Pin

Internal Pull-Up0 = enable (default GPIO 12-44)1 = disable (default GPIO 0-11)

GPxPUD

Input Qualification

(GPIO 0-44) GPxQSEL1GPxQSEL2GPxCTRL

* See device datasheet for pin function selection matrices



Qualification available on ports A & B (GPIO 0 - 44) onlyIndividually selectable per pin

no qualification (peripherals only)sync to SYSCLKOUT onlyqualify 3 samplesqualify 6 samples

AIO pins are fixed as ‘sync to SYSCLKOUT’

F2803x GPIO Input Qualification

InputQualificationpin

to GPIO and peripheral modules

SYSCLKOUT

T T T

samples taken

T = qual period

F2803x GPIO Input Qual RegistersGpioCtrlRegs.register (lab file: Gpio.c)

00 = sync to SYSCLKOUT only *01 = qual to 3 samples10 = qual to 6 samples11 = no sync or qual (for peripheral only; GPIO same as 00)

00h no qualification (SYNC to SYSCLKOUT) *01h QUALPRD = SYSCLKOUT/202h QUALPRD = SYSCLKOUT/4… … …

FFh QUALPRD = SYSCLKOUT/510

GPAQSEL1 / GPAQSEL2 / GPBQSEL116 pins configured per register

031

QUALPRD0QUALPRD1QUALPRD2QUALPRD3

GPACTRL / GPBCTRL31 24 16 8 0

B: reserved reserved GPIO44-40 GPIO39-32 A: GPIO31-24 GPIO23-16 GPIO15-8 GPIO7-0

* reset default



F2803x GPIO Control RegistersGpioCtrlRegs.register (lab file: Gpio.c)

Register DescriptionGPACTRL GPIO A Control Register [GPIO 0 – 31]GPAQSEL1 GPIO A Qualifier Select 1 Register [GPIO 0 – 15]GPAQSEL2 GPIO A Qualifier Select 2 Register [GPIO 16 – 31]GPAMUX1 GPIO A Mux1 Register [GPIO 0 – 15]GPAMUX2 GPIO A Mux2 Register [GPIO 16 – 31]GPADIR GPIO A Direction Register [GPIO 0 – 31]GPAPUD GPIO A Pull-Up Disable Register [GPIO 0 – 31]GPBCTRL GPIO B Control Register [GPIO 32 – 44]GPBQSEL1 GPIO B Qualifier Select 1 Register [GPIO 32 – 44]GPBMUX1 GPIO B Mux1 Register [GPIO 32 – 44]GPBDIR GPIO B Direction Register [GPIO 32 – 44]GPBPUD GPIO B Pull-Up Disable Register [GPIO 32 – 44]AIOMUX1 ANALOG I/O Mux1 Register [AIO 0 – 15]AIODIR ANALOG I/O Direction Register [AIO 0 – 15]

F2803x GPIO Data RegistersGpioDataRegs.register (lab file: Gpio.c)

Register DescriptionGPADAT GPIO A Data Register [GPIO 0 – 31]GPASET GPIO A Data Set Register [GPIO 0 – 31]GPACLEAR GPIO A Data Clear Register [GPIO 0 – 31]GPATOGGLE GPIO A Data Toggle [GPIO 0 – 31]GPBDAT GPIO B Data Register [GPIO 32 – 44]GPBSET GPIO B Data Set Register [GPIO 32 – 44]GPBCLEAR GPIO B Data Clear Register [GPIO 32 – 44]GPBTOGGLE GPIO B Data Toggle [GPIO 32 – 44]AIODAT ANALOG I/O Data Register [AIO 0 – 15]AIOSET ANALOG I/O Data Set Register [AIO 0 – 15]AIOCLEAR ANALOG I/O Data Clear Register [AIO 0 – 15]AIOTOGGLE ANALOG I/O Data Toggle [AIO 0 – 15]


External Interrupts

External Interrupts External Interrupts

3 external interrupt signals: XINT1, XINT2 and XINT3

XINT1, XINT2 and XINT3 can be mapped to any of GPIO0-31

XINT1, XINT2 and XINT3 also each have a free-running 16-bit counter that measures the elapsed time between interrupts

The counter resets to zero each time the interrupt occurs

External Interrupt Registers

Interrupt Pin Selection Register Configuration Register Counter Register(GpioIntRegs.register) (XIntruptRegs.register) (XIntruptRegs.register)

XINT1 GPIOXINT1SEL XINT1CR XINT1CTRXINT2 GPIOXINT2SEL XINT2CR XINT2CTRXINT3 GPIOXINT3SEL XINT3CR XINT3CTR

Pin Selection Register chooses which pin(s) the signal comes out onConfiguration Register controls the enable/disable and polarityCounter Register holds the interrupt counter


Low Power Modes

Low Power Modes Low Power Modes

Low PowerMode

CPU LogicClock

PeripheralLogic Clock

WatchdogClock

PLL /OSC

Normal Run

IDLE

STANDBY

HALT

on

off

off

off

on

on

off

off

on

on

on

off

on

on

on

off

See device datasheet for power consumption in each mode

Low Power Mode Control Register 0SysCtrlRegs.LPMCR0 (lab file: SysCtrl.c)

1 - 07 - 214 - 8

LPM0WDINTE QUALSTDBYreserved

Low Power Mode Selection00 = Idle (default)01 = Standby1x = Halt

Wake from STANDBYGPIO signal qualification *

000000 = 2 OSCCLKs000001 = 3 OSCCLKs

111111 = 65 OSCCLKS (default)

... ... ...

15

Watchdog Interrupt wake device from

STANDBY0 = disable (default)1 = enable

Low Power Mode Entering1. Set LPM bits2. Enable desired exit interrupt(s)3. Execute IDLE instruction4. The power down sequence of the hardware

depends on LP mode

* QUALSTDBY will qualify the GPIO wakeup signal in series with the GPIO port qualification. This is useful when GPIO port qualification is not available or insufficient for wake-up purposes.


Low Power Modes

Low Power Mode Exit

IDLE

STANDBY

HALT

RESET

yes

yes

yes

Any Enabled Interrupt

yes

no

no

yes

yes

no

ExitInterrupt

Low PowerMode

WatchdogInterrupt

GPIO Port A Signal

yes

yes

yes

GPIO Low Power Wakeup SelectSysCtrlRegs.GPIOLPMSEL

Wake device fromHALT and STANDBY mode

(GPIO Port A)0 = disable (default)1 = enable

0

GPIO2

GPIO14 GPIO8GPIO11

GPIO51234567

89101112131415

GPIO0GPIO1GPIO4 GPIO3

GPIO9

GPIO6

GPIO10

GPIO7

GPIO12GPIO13GPIO15

16

GPIO18

GPIO30 GPIO24GPIO27

GPIO2117181920212223

2425262728293031

GPIO16GPIO17GPIO20 GPIO19

GPIO25

GPIO22

GPIO26

GPIO23

GPIO28GPIO29GPIO31


Register Protection

Register Protection

CPU pipeline protects W-R order for the same addressWrite-Read protection mechanism protects W-R order for different addresses

Peripheral Frame 1 and Peripheral Frame 2 zones protectedWrite-read protection mode bit ENPROT located in the DEVICECNF register is enabled by default

Write-Read ProtectionDevEmuRegs.DEVICECNF.bit.ENPROT

Suppose you need to write to a peripheral register and then read a different register for the same peripheral (e.g., write to control, read from status register)?

Peripheral Frame RegistersPF0

eCANCOMPePWMeCAPeQEPLIN

GPIO

PF1System Control

SPISCI

WatchdogXINTADCI2C

Protected address:0x4000 - 0x7FFF

EALLOW Protection (1 of 2)

EALLOW stands for Emulation AllowCode access to protected registers allowed only when EALLOW = 1 in the ST1 registerThe emulator can always access protected registersEALLOW bit controlled by assembly level instructions

‘EALLOW’ sets the bit (register access enabled)‘EDIS’ clears the bit (register access disabled)

EALLOW bit cleared upon ISR entry, restored upon exit


Register Protection

EALLOW Protection (2 of 2)

asm(" EALLOW"); // enable protected register access

SysCtrlRegs.WDKEY=0x55; // write to the register

asm(" EDIS"); // disable protected register access

EALLOW register access C-code example:

Device EmulationFlashCode Security ModulePIE Vector TableLIN (some registers)eCANA/B (control registers only; mailbox RAM not protected)ePWM1-7 and COMP1-3 (some registers)GPIO (control registers only)System Control

See device datasheet and peripheral users guides for detailed listings

The following registers are protected:


Lab 5: System Initialization

Lab 5: System Initialization Objective

The objective of this lab is to perform the processor system initialization. Additionally, the peripheral interrupt expansion (PIE) vectors will be initialized and tested using the information discussed in the previous module. This initialization process will be used again in all of the lab exercises throughout this workshop. The system initialization for this lab will consist of the following:

• Setup the clock module – PLL, LOSPCP = /4, low-power modes to default values, enable all module clocks

• Disable the watchdog – clear WD flag, disable watchdog, WD prescale = 1 • Setup watchdog system and control register – DO NOT clear WD OVERRIDE bit, WD

generate a CPU reset • Setup shared I/O pins – set all GPIO pins to GPIO function (e.g. a "00" setting for GPIO

function, and a “01”, “10”, or “11” setting for a peripheral function.)

The first part of the lab exercise will setup the system initialization and test the watchdog operation by having the watchdog cause a reset. In the second part of the lab exercise the PIE vectors will be added and tested by using the watchdog to generate an interrupt. This lab will make use of the DSP2803x C-code header files to simplify the programming of the device, as well as take care of the register definitions and addresses. Please review these files, and make use of them in the future, as needed.

Procedure

Create Project File 1. Create a new project called Lab5.pjt in C:\C28x\Labs\Lab5 and add the

following files to it:

CodeStartBranch.asm Lab_5_6_7.cmdDelayUs.asm Main_5.cDSP2803x_GlobalVariableDefs.c SysCtrl.cDSP2803x_Headers_nonBIOS.cmd Watchdog.cGpio.c

Note that include files, such as DSP2803x_Device.h and Lab.h, are automatically added at project build time. (Also, DSP2803x_DefaultIsr.h is automatically added and will be used with the interrupts in the second part of this lab exercise).



Project Build Options 2. We need to setup the search path to include the peripheral register header files. Click:

Project Build Options…

Select the Compiler tab. In the Preprocessor Category, find the Include Search Path (-i) box and enter:

..\DSP2803x_headers\include

This is the path for the header files.

3. Select the Linker tab and set the Stack Size to 0x200.

4. Setup the compiler run-time support library. In the Libraries Category, find the Include Libraries (-l) box and enter: rts2800_ml.lib. Select OK and the Build Options window will close.

Modify Memory Configuration 5. Open and inspect the linker command file Lab_5_6_7.cmd. Notice that the user

defined section “codestart” is being linked to a memory block named BEGIN_M0. The codestart section contains code that branches to the code entry point of the project. The bootloader must branch to the codestart section at the end of the boot process. Recall that the "Jump to M0 SARAM" bootloader mode branches to address 0x000000 upon bootloader completion.

Modify the linker command file Lab_5_6_7.cmd to create a new memory block named BEGIN_M0: origin = 0x000000, length = 0x0002, in program memory. You will also need to modify the existing memory block M0SARAM in data memory to avoid any overlaps with this new memory block.

Setup System Initialization 6. Modify SysCtrl.c and Watchdog.c to implement the system initialization as

described in the objective for this lab.

7. Open and inspect Gpio.c. Notice that the shared I/O pins have been set to the GPIO function. Save your work and close the modified files.

Build and Load 8. Click the “Build” button and watch the tools run in the build window. The output

file should automatically load.

9. Under Debug on the menu bar click “Reset CPU”.



10. Under GEL on the menu bar click: EMU Boot Mode Select EMU_BOOT_SARAM. This has the debugger load values into EMU_KEY and EMU_BMODE so that the bootloader will jump to "M0 SARAM" at 0x000000.

11. Under Debug on the menu bar click “Go Main”. You should now be at the start of Main().

Run the Code – Watchdog Reset 12. Place the cursor in the “main loop” section (on the asm(“ NOP”); instruction

line) and right click the mouse key and select Run To Cursor. This is the same as setting a breakpoint on the selected line, running to that breakpoint, and then removing the breakpoint.

13. Place the cursor on the first line of code in main() and set a breakpoint by right clicking the mouse key and select Toggle Software Breakpoint. Notice that line is highlighted with a red dot indicating that the breakpoint has been set. Alternately, you can double-click in the gray field to the left of the code line to set the breakpoint. The breakpoint is set to prove that the watchdog is disabled. If the watchdog causes a reset, code execution will stop at this breakpoint.

14. Run your code for a few seconds by using the <F5> key, or using the Run button on the vertical toolbar, or using Debug Run on the menu bar. After a few seconds halt your code by using Shift <F5>, or the Halt button on the vertical toolbar. Where did your code stop? Are the results as expected? If things went as expected, your code should be in the “main loop”.

15. Modify the InitWatchdog() function to enable the watchdog (WDCR). This will enable the watchdog to function and cause a reset. Save the file and click the “Build” button.

16. Reset the CPU by performing the following steps: Click on Debug Reset CPU Next click Debug Go Main

17. Like before, place the cursor in the “main loop” section (on the asm(“ NOP”); instruction line) and right click the mouse key and select Run To Cursor..

18. Run your code. Where did your code stop? Are the results as expected? If things went as expected, your code should have stopped at the breakpoint. What happened is as follows. While the code was running, the watchdog timed out and reset the processor. The reset vector was then fetched and the ROM bootloader began execution. Since the device is in emulation boot mode (i.e. the emulator is connected) the bootloader read the EMU_KEY and EMU_BMODE values from the PIE RAM. These values were previously set for boot to M0 SARAM bootmode when we invoked the EMU_BOOT_SARAM GEL function earlier in this lab. Since these values did not change and are not affected by reset, the bootloader transferred execution to the beginning of our code at address 0x000000 in the M0SARAM, and execution continued until the breakpoint was hit in main().



Setup PIE Vector for Watchdog Interrupt The first part of this lab exercise used the watchdog to generate a CPU reset. This was tested using a breakpoint set at the beginning of main(). Next, we are going to use the watchdog to generate an interrupt. This part will demonstrate the interrupt concepts learned in the previous module.

19. Add the following files to the project: DefaultIsr_5.c PieCtrl_5_6_7_8_9_10.c PieVect_5_6_7_8_9_10.c Check your files list to make sure the files are there.

20. In Main_5.c, add code to call the InitPieCtrl() function. There are no passed parameters or return values, so the call code is simply: InitPieCtrl();

21. Using the “PIE Interrupt Assignment Table” shown in the previous module find the location for the watchdog interrupt, “WAKEINT”. This will be used in the next step.

PIE group #: # within group:

22. Modify main() to do the following: - Enable global interrupts (INTM bit)

Then modify InitWatchdog() to do the following: - Enable the "WAKEINT" interrupt in the PIE (Hint: use the PieCtrlRegs structure) - Enable the appropriate core interrupt in the IER register

23. In Watchdog.c modify the system control and status register (SCSR) to cause the watchdog to generate a WAKEINT rather than a reset. Save all changes to the files.

24. Open and inspect DefaultIsr_5.c. This file contains interrupt service routines. The ISR for WAKEINT has been trapped by an emulation breakpoint contained in an inline assembly statement using “ESTOP0”. This gives the same results as placing a breakpoint in the ISR. We will run the lab exercise as before, except this time the watchdog will generate an interrupt. If the registers have been configured properly, the code will be trapped in the ISR.

25. Open and inspect PieCtrl_5_6_7_8_9_10.c. This file is used to initialize the PIE RAM and enable the PIE. The interrupt vector table located in PieVect_5_6_7_8_9_10.c is copied to the PIE RAM to setup the vectors for the interrupts. Close the modified and inspected files.

Build and Load 26. Click the “Build” button. Next reset the CPU, and then “Go Main”.



Run the Code – Watchdog Interrupt 27. Place the cursor in the “main loop” section, right click the mouse key and select

Run To Cursor.

28. Run your code. Where did your code stop? Are the results as expected? If things went as expected, your code should stop at the “ESTOP0” instruction in the WAKEINT ISR.

End of Exercise

Note: By default, the watchdog timer is enabled out of reset. Code in the file CodeStartBranch.asm has been configured to disable the watchdog. This can be important for large C code projects (ask your instructor if this has not already been explained). During this lab exercise, the watchdog was actually re-enabled (or disabled again) in the file Watchdog.c.


Analog-to-Digital Converter and Comparator

Introduction This module explains the operation of the analog-to-digital converter and comparator. The ADC system consists of a 12-bit analog-to-digital converter with up to 16 analog input channels. The analog input channels have a full range analog input of 0 to 3.3 volts or VREFHI/VREFLO ratiometric. Two input analog multiplexers are available, each supporting up to 8 analog input channels. Each multiplexer has its own dedicated sample and hold circuit. Therefore, sequential, as well as simultaneous sampling is supported. The ADC system is start-of-conversion (SOC) based where each independent SOCx (where x = 0 to 15) register configures the trigger source that starts the conversion, the channel to convert, and the acquisition (sample) window size. Up to 16 results registers are used to store the conversion values. Conversion triggers can be performed by an external trigger pin, software, an ePWM or CPU timer interrupt event, or a generated ADCINT1/2 interrupt.


Understand the operation of the Analog-to-Digital converter (ADC) and ComparatorUse the ADC to perform data acquisition

C2000 Piccolo Workshop - Analog-to-Digital Converter 6 - 1

Module Topics

Module Topics Analog-to-Digital Converter and Comparator ....................................................................................... 6-1

Module Topics......................................................................................................................................... 6-2 Analog-to-Digital Converter................................................................................................................... 6-3

ADC Block and Functional Diagrams ................................................................................................ 6-3 ADC Triggering.................................................................................................................................. 6-4 ADC Conversion Priority ................................................................................................................... 6-5 ADC Clock and Timing...................................................................................................................... 6-7 ADC Converter Registers ................................................................................................................... 6-8 ADC Calibration and Reference........................................................................................................6-13

Comparator............................................................................................................................................6-15 Comparator Block Diagram...............................................................................................................6-15 Comparator Registers ........................................................................................................................6-16

Lab 6: Analog-to-Digital Converter ......................................................................................................6-17

6 - 2 C2000 Piccolo Workshop - Analog-to-Digital Converter

Analog-to-Digital Converter


ADC Block and Functional Diagrams

ADC Module Block Diagram

12-bit A/DConverter

SOC

EOCx

ADCINA0ADCINA1

ADCINA7

ADCINB0ADCINB1

ADCINB7

S/HA

S/HB

MUX

MUXA

RESULT0RESULT1RESULT2

RESULT15

ResultMUX

MUXB

ADCGeneration

LogicADC full-scale input range is

0 to 3.3V

CHSEL ADCInterrupt

Logic

SOC0 TRIGSEL CHSEL ACQPSSOC1 TRIGSEL CHSEL ACQPSSOC2 TRIGSEL CHSEL ACQPSSOC3 TRIGSEL CHSEL ACQPS

SOC15 TRIGSEL CHSEL ACQPS SOC

xTr

igge

rs

ADCINT1-9

Software

External Pin(GPIO/XINT2_ADCSOC)

EPWMxSOCA (x = 1 to 7)EPWMxSOCB (x = 1 to 7)

CPU Timer (0,1,2)

SOCx Signal ADCINT1ADCINT2

SOCx Configuration Registers

ADC SOCx Functional Diagram

This block diagram is replicated 16 times

Software TriggerTINT0 (CPU Timer 0)TINT1 (CPU Timer 1)TINT2 (CPU Timer 2)

XINT2_ADCSOC (GPIO)SOCA (ePWM1)SOCB (ePWM1)

SOCA (ePWM7)SOCB (ePWM7)

Trigger

noneADCINT1ADCINT2

Re-Trigger

ADCINT1ADCINT2ADCINT3ADCINT4ADCINT5ADCINT6ADCINT7ADCINT8ADCINT9

ChannelSelect

SampleWindow

ResultRegisterS

OCx

EOCx

ADCSOCxCTL

ADCSOCFRC1

ADCINTSOCSEL1ADCINTSOCSEL2

INTSELxNy

ADCRESULTx



ADC Triggering

Example – ADC Triggering (1 of 2)

Sample A2 B3 A7 when ePWM1 SOCB is generated and then generate ADCINT1n:

ChannelA2

Sample7 cycles Result0

ChannelB3


ChannelA7


SOC0

SOC1

SOC2

no interrupt

no interrupt

ADCINT1n

SOCB (ETPWM1)

As above, but also sample A0 B0 A5 continuously and generate ADCINT2n:

ChannelA2


ChannelB3


ChannelA7


SOC0

SOC1

SOC2

no interrupt

no interrupt

ADCINT1n

SOCB (ETPWM1)

ChannelA0


ChannelB0


ChannelA5


SOC3

SOC4

SOC5

no interrupt

no interrupt

ADCINT2n

ADCINT2n

Software Trigger

Example – ADC Triggering (2 of 2)

Sample all channels continuously and provide Ping-Pong interrupts to CPU/system:

ChannelA0:B0

Sample7 cycles

SOC0 no interruptADCINT2n

Software Trigger Result0Result1

ChannelA1:B1

Sample7cycles

SOC2 no interruptResult2Result3

ChannelA2:B2

Sample7 cycles


ChannelA3:B3

Sample7 cycles

SOC6 Result6Result7

ChannelA4:B4

Sample7 cycles


ChannelA5:B5

Sample7 cycles


ChannelA6:B6

Sample7 cycles


ChannelA7:B7

Sample7 cycles

SOC14 Result14Result15

ADCINT1n

ADCINT2n



ADC Conversion Priority

ADC Conversion Priority

When multiple SOC flags are set at the same time – priority determines the order in which they are converted

Round Robin Priority (default)No SOC has an inherent higher priority than anotherPriority depends on the round robin pointer

High PriorityHigh priority SOC will interrupt the round robin wheel after current conversion completes and insert itself as the next conversionAfter its conversion completes, the round robin wheel will continue where it was interrupted

Conversion Priority Functional Diagram

Round Robin PointerPoints to the last converted

round robin SOCx anddetermines order

of conversions

SOC PriorityDetermines cutoff point

for high priority andround robin mode

SOC0SOC1SOC2SOC3SOC4SOC5SOC6SOC7SOC8SOC9

SOC10SOC11SOC12SOC13SOC14SOC15

Rou

nd R

obin

Hig

h Pr

iorit

y

SOCPRIORITY

RRPOINTER

AdcRegs.SOCPRICTL



Round Robin Priority Example

SOC0 SOC

1SOC

2

SOC3

SOC4

SOC5

SOC6

SOC7SOC

8

SOC9

SOC10

SOC11

SOC12

SOC13

SOC14

SOC15

RRPOINTER

SOC7 trigger received

SOC7 is converted; RRPOINTER now points to SOC7; SOC8 is now highest RR priority

SOC2 & SOC12 triggers received simultaneously

SOC12 is converted; RRPOINTER points to SOC12; SOC13 is now highest RR priority


SOCPRIORITY configured as 0; RRPOINTER configured as 15; SOC0 is highest RR priority

High Priority Example

SOC4 SOC

5

SOC0 SOC

6

SOC7

SOC8

SOC9SOC

10

SOC11

SOC12

SOC13

SOC14

SOC15

RRPOINTER

SOC1

SOC2

SOC3

High PrioritySOC7 trigger received


SOC2 is converted; RRPOINTER stays pointing to SOC7


SOCPRIORITY configured as 4; RRPOINTER configured as 15; SOC4 is highest RR priority

SOC2 & SOC12 triggers received simultaneously



ADC Clock and Timing

ADC Clocking FlowInternal OSC1

(10 MHz)

ADCCLK (60 MHz)To ADC pipeline

sampling windowACQ_PS

bits

ADCSOCxCTL

0110b

SYSCLKOUT(60 MHz)

PLLSTS

DIVSELbits

10b (/2)

To CPU

sampling window = (ACQ_PS + 1)*(1/ADCCLK)

PCLKCR0.ADCENCLK = 1

PLLCR

DIVbits

1100b (x12)

ADC Timing – Sequential Sampling

7 ClocksSample

6 Clocks 7 ClocksConvert

2 ClocksWrite

2 ClocksLatch

Generate EarlyInterrupt

Generate LateInterrupt

Start Sampling Next Channel

Max Continuous Sampling:

60 MHz13 cycles / 1 sample = 4.62 MSPS




ADC Timing – Simultaneous Sampling

7 ClocksSample

13 ClocksConvert “A” Channel

2 ClocksWrite

2 ClocksLatch

Generate EarlyInterrupt “A” Channel Generate Late

Interrupt “A” Channel

Start Sampling Next Channel&

Generate EarlyInterrupt “B” Channel

6 Clocks 7 ClocksConvert “B” Channel

2 ClocksWrite

Generate LateInterrupt “B” Channel

Max Continuous Sampling:



ADC Converter Registers

Analog-to-Digital Converter RegistersAdcRegs.register (lab file: Adc.c)

ADCCTL1 Control 1 RegisterADCSOCxCTL SOC0 to SOC15 Control RegistersADCINTSOCSELx Interrupt SOC Selection 1 and 2 RegistersADCSAMPLEMODE Sampling Mode RegisterADCSOCFLG1 SOC Flag 1 RegisterADCSOCFRC1 SOC Force 1 RegisterADCSOCOVF1 SOC Overflow 1 RegisterADCSOCOVFCLR1 SOC Overflow Clear 1 RegisterINTSELxNy Interrupt x and y Selection RegistersADCINTFLG Interrupt Flag RegisterADCINTFLGCLR Interrupt Flag Clear RegisterADCINTOVF Interrupt Overflow RegisterADCINTOVFCLR Interrupt Overflow Clear RegisterSOCPRICTL SOC Priority Control Register ADCREFTRIM Reference Trim RegisterADCOFFTRIM Offset Trim RegisterADCREV Revision Register – reservedADCRESULTx ADC Result 0 to 15 Registers

Register Description

Note: ADCRESULTx is located in AdcResult.register and not in AdcRegs



ADC Control Register 1AdcRegs.ADCCTL1

ADC Enable0 = ADC disable1 = ADC enable

ADC Module Reset0 = no effect1 = reset (set back to 0

by ADC logic)

ADCENABLE ADCBSY ADCBSYCHNRESET12 - 815

Upper Register:

14 13

ADC Busy0 = ADC busy1 = ADC available

ADC Busy ChannelWhen ADCBSY =0: last channel converted1: channel currently processing

00h = ADCINA0 08h = ADCINB001h = ADCINA1 09h = ADCINB102h = ADCINA2 0Ah = ADCINB203h = ADCINA3 0Bh = ADCINB304h = ADCINA4 0Ch = ADCINB405h = ADCINA5 0Dh = ADCINB506h = ADCINA6 0Eh = ADCINB607h = ADCINA7 0Fh = ADCINB7

ADC Control Register 1AdcRegs.ADCCTL1

ADC Power Down0 = analog circuitry

powered down1 = analog circuitry

powered up

ADC ReferenceSelect0 = internal 1 = external

(VREFHI/VREFLO)

ADCBGPWN ADCREFPWDADCPWN reserved7

Lower Register:

VREFLOCONV

INTPULSEPOS

6 5 4 3 2 0

ADC BandgapPower Down0 = bandgap circuitry

powered down1 = bandgap circuitry

powered up

ADC ReferencePower Down0 = reference circuitry

powered down1 = reference circuitry

powered up

TEMPCONV

ADCREFSEL

1

TemperatureSensor Convertcurrently not used0 = only valid setting

INT PulseGeneration Control0 = beginning of

conversion 1 = one cycle prior

to result

VREFLO Convert0 = not connected 1 = connected (B5)



ADC SOC0 – SOC15 Control RegistersAdcRegs.ADCSOCxCTL

TRIGSEL reserved15 - 11 10 9 - 6 5 - 0

CHSEL ACQPS

SOCx TriggerSource Select

SOCx ChannelSelect

SOCx AcquisitionPrescale (S/H window)

0h = ADCINA0 0h = ADCINA0/B01h = ADCINA1 1h = ADCINA1/B12h = ADCINA2 2h = ADCINA2/B23h = ADCINA3 3h = ADCINA3/B34h = ADCINA4 4h = ADCINA4/B45h = ADCINA5 5h = ADCINA5/B56h = ADCINA6 6h = ADCINA6/B67h = ADCINA7 7h = ADCINA7/B78h = ADCINB0 8h – Fh = invalid 9h = ADCINB1Ah = ADCINB2Bh = ADCINB3Ch = ADCINB4Dh = ADCINB5Eh = ADCINB6Fh = ADCINB7

Sequential S/M(SIMULENx=0)

Simultaneous S/M(SIMULENx=1)

00h = software01h = CPU Timer 002h = CPU Timer 103h = CPU Timer 204h = XINT2SOC05h = ePWM1SOCA06h = ePWM1SOCB07h = ePWM2SOCA08h = ePWM2SOCB 09h = ePWM3SOCA0Ah = ePWM3SOCB0Bh = ePWM4SOCA0Ch = ePWM4SOCB0Dh = ePWM5SOCA0Eh = ePWM5SOCB0Fh = ePWM6SOCA10h = ePWM6SOCB11h = ePWM7SOCA12h = ePWM7SOCB

00h – 05h = invalid06h = 7 cycles long07h = 8 cycles long08h = 9 cycles long09h = 10 cycles long

3Fh = 64 cycles long

Sampling Window

ADC Interrupt Trigger SOC Select Registers 1 & 2AdcRegs.ADCINTSOCSELx

15 - 14SOC15 SOC14 SOC13 SOC12 SOC11 SOC10 SOC9 SOC8

13 - 12 11 - 10 9 - 8 7 - 6 5 - 4 3 - 2 1 - 0

15 - 14SOC7 SOC6 SOC5 SOC4 SOC3 SOC2 SOC1 SOC0

13 - 12 11 - 10 9 - 8 7 - 6 5 - 4 3 - 2 1 - 0

ADCINTSOCSEL2

ADCINTSOCSEL1

SOCx ADC Interrupt SelectSelects which, if any, ADCINT triggers SOCx00 = no ADCINT will trigger SOCx (TRIGSEL field determines SOCx trigger)01 = ADCINT1 will trigger SOCx (TRIGSEL field ignored)10 = ADCINT2 will trigger SOCx (TRIGSEL field ignored)11 = invalid selection



ADC Sample Mode RegisterAdcRegs.ADCSAMPLEMODE

reserved

15 - 8

7SIMULEN14 SIMULEN12 SIMULEN10 SIMULEN8 SIMULEN6 SIMULEN4 SIMULEN2 SIMULEN0

6 5 4 3 2 1 0

Simultaneous Sampling EnableCouples SOCx and SOCx+1 in simultaneous sampling mode0 = single sample mode for SOCx and SOCx+11 = simultaneous sample mode for SOCx and SOCx+1

SOC Priority Control RegisterAdcRegs.SOCPRICTL

reserved15 - 11 10 - 5 4 - 0

RRPOINTER SOCPRIORITY

Round Robin PointerPoints to the last converted

round robin SOCx anddetermines order

of conversions

SOC PriorityDetermines cutoff point

for high priority andround robin mode

00h = round robin mode for all channels01h = SOC0 high priority, SOC1-15 round robin02h = SOC0-1 high priority, SOC2-15 round robin03h = SOC0-2 high priority, SOC3-15 round robin04h = SOC0-3 high priority, SOC4-15 round robin05h = SOC0-4 high priority, SOC5-15 round robin06h = SOC0-5 high priority, SOC6-15 round robin07h = SOC0-6 high priority, SOC7-15 round robin08h = SOC0-7 high priority, SOC8-15 round robin09h = SOC0-8 high priority, SOC9-15 round robin0Ah = SOC0-9 high priority, SOC10-15 round robin0Bh = SOC0-10 high priority, SOC11-15 round robin0Ch = SOC0-11 high priority, SOC12-15 round robin0Dh = SOC0-12 high priority, SOC13-15 round robin0Eh = SOC0-13 high priority, SOC14-15 round robin0Fh = SOC0-14 high priority, SOC15 round robin10h = all SOCs high priority (arbitrated by SOC #)1xh = invalid selection

00h = SOC0 last converted, SOC1 highest priority01h = SOC1 last converted, SOC2 highest priority02h = SOC2 last converted, SOC3 highest priority03h = SOC3 last converted, SOC4 highest priority04h = SOC4 last converted, SOC5 highest priority05h = SOC5 last converted, SOC6 highest priority06h = SOC6 last converted, SOC7 highest priority07h = SOC7 last converted, SOC8 highest priority08h = SOC8 last converted, SOC9 highest priority09h = SOC9 last converted, SOC11 highest priority0Ah = SOC10 last converted, SOC11 highest priority0Bh = SOC11 last converted, SOC12 highest priority0Ch = SOC12 last converted, SOC13 highest priority0Dh = SOC13 last converted, SOC14 highest priority0Eh = SOC14 last converted, SOC15 highest priority0Fh = SOC15 last converted, SOC0 highest priority1xh = invalid selection20h = reset value (no SOC has been converted)



Interrupt Select x and y RegisterAdcRegs.INTSELxNy

INTxE INTxSELINTxCONTreserved

7 456 - 0

INTyE INTySELINTyCONTreserved15 12 - 81314

Where x/y = 1/2, 3/4, 5/6, 7/8, 9/10 and 10 is reserved

00h = EOC0 is trigger for ADCINTx/y01h = EOC1 is trigger for ADCINTx/y02h = EOC2 is trigger for ADCINTx/y03h = EOC3 is trigger for ADCINTx/y04h = EOC4 is trigger for ADCINTx/y05h = EOC5 is trigger for ADCINTx/y06h = EOC6 is trigger for ADCINTx/y07h = EOC7 is trigger for ADCINTx/y08h = EOC8 is trigger for ADCINTx/y09h = EOC9 is trigger for ADCINTx/y0Ah = EOC10 is trigger for ADCINTx/y0Bh = EOC11 is trigger for ADCINTx/y0Ch = EOC12 is trigger for ADCINTx/y0Dh = EOC13 is trigger for ADCINTx/y0Eh = EOC14 is trigger for ADCINTx/y0Fh = EOC15 is trigger for ADCINTx/y1xh = invalid value

ADCINTx/y EOC Source Select

ADCINTx/yInterrupt Enable0 = disable1 = enable

ADCINTx/yContinuousMode Enable0 = one-shot pulse

generated (until flagcleared by user)

1 = pulse generated foreach EOC

ADC Conversion Result Registers

Sequential Sampling Mode (SIMULENx = 0)After ADC completes a conversion of an SOCx, the digital result is placed in the corresponding ADCRESULTx register

Simultaneous Sampling Mode (SIMULENx = 1)After ADC completes a conversion of a channel pair, the digital results are found in the corresponding ADCRESULTxand ADCRUSULTx+1 registers

Input Digital AdcResult.Voltage Result ADCRESULTx

3.3 FFFh 0000|1111|1111|11111.65 7FFh 0000|0111|1111|11110.00081 1h 0000|0000|0000|00010 0h 0000|0000|0000|0000

LSBMSB15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0

AdcResult.ADCRESULTx, x = 0 - 15



How Can We Handle Signed Input Voltages?Example: -1.65 V ≤ Vin ≤ +1.65 V

1) Add 1.65 volts to the analog input

Vin

1.65V ADCINx

GND

ADCLO

-+

R

R

R-+

R

RC28x

#include “DSP2803x_Device.h”#define offset 0x07FFvoid main(void){

int16 value; // signed

value = AdcResult.ADCRESULT0 – offset;}

2) Subtract “1.65” from the digital result

ADC Calibration and Reference

Built-In ADC CalibrationTI reserved OTP contains device specific calibration data for the ADC and internal oscillatorsThe Boot ROM contains a Device_cal() routine that copies the calibration data to their respective registersDevice_cal() must be run to meet the ADC and oscillator specs in the datasheet

The Bootloader automatically calls Device_cal() such that no action is normally required by the userIf the bootloader is bypassed (e.g., during development) Device_cal() should be called by the application:

A GEL function using CCS is also available as part of the Peripheral Register Header Files to accomplish this

#define Device_cal (void (*)(void))0x3D7C80

void main(void)

{

(*Device_cal)(); // call Device_cal()

}



If the offset and gain errors in the datasheet* are unacceptable for your application, or you want to also compensate for board level errors (e.g., sensor or amplifier offset), you can manually calibrateOffset error

Compensated in analog with the ADCOFFTRIM registerNo reduction in full-scale rangeConfigure input B5 to VREFLO, set ADCOFFTRIM to maximum offset error, and take a readingRe-adjust ADCOFFTRIM to make result zero

Gain errorCompensated in softwareSome loss in full-scale rangeRequires use of a second ADC input pin and an upper-range reference voltage on that pin; see “TMS320280x and TMS320F2801x ADC Calibration” appnote #SPRAAD8 for more information

Tip: To minimize mux-to-mux variation effects, put your most critical signals on a single mux and use that mux for calibration inputs

Manual ADC Calibration

* +/-15 LSB offset, +/-30 LSB gain. See device datasheet for exact specifications

CH

CH

MUX

VREFLOCONVVREFLO

B5

ADCOFFTRIM

12-bitADC

ADC Reference SelectionAdcRegs.ADCREFSEL

The internal reference has temperature stability of ~50 PPM/°C*The internal reference (default) will convert an applied input voltage to a fixed scale of 0 to 3.3 V rangeIf this is not sufficient for your application, there is the option to use an external reference*

External reference will scale an input voltage range from VREFLO to VREFHI (ratiometric)The reference value changes the 0 - 3.3 V full-scale range of the ADC

The ADCREFSEL in ADCCTL1 controls the reference choice

* See device datasheet for exact specifications and ADC reference hardware connections

2 - 015 - 5ADCREFSEL

ADC Reference Selection0 = internal (default)1 = external VREFHI/VREFLO pins

used for reference generation

reserved4 3


Comparator

Comparator

Comparator Block Diagram

Comparator

COMP110-bitDAC

AIO2AIO10

COMP1OUT

COMP310-bitDAC

AIO6AIO14

COMP3OUT

COMP210-bitDAC

AIO4AIO12

COMP2OUTADC

A0

A1

A2

A3

A4

A5

A6

A7

B0

B1

B2

B3

B4

B5

B6

B7

Comparator Block Diagram

DACVAL * (VDDA – VSSA)1023

V =

DAC Reference Comparator Truth TableVoltages OutputVoltage A < Voltage B 0Voltage A > Voltage B 1

0

10

1

+

COMPx

-

ePWMEvent

Trigger&

GPIOMUX

Sync/Qual

10-bitDAC

COMPSTS

VDDA

VSSA

Input Pin B

Input Pin A

1

0

COMPSOURCEDACVAL CMPINV

COMPDACE

SYNCSEL

QUALSEL

SYSCLKOUT COMPxTRIPV


Comparator

Comparator Registers

Comparator Registers

reserved15 - 10

DACVAL9 - 0

DAC ValueScales output of DAC from 0 – 1023

Value = 0 – 3FFh

AdcRegs.DACVAL – DAC Value Register

reserved15 - 1

COMPSTS0

AdcRegs.COMPSTS – Compare Output Status Register

Logical latched value of the comparator

reserved15 - 9 7 - 3

SYNCSEL QUALSEL CMPINV COMPSOURCE COMPDACE8 2 1

AdcRegs.COMPCTL – Compare Control Register

Synchronization SelectOutput before being feedto ETPWM/GPIO blocks0 = Asynchronous1 = Synchronous

Comparator/DAC Enable0 = disable1 = enable

ComparatorSource0 = DAC1 = pin

Invert0 = passed1 = inverted

QualificationPeriod0h = passed1h = 2 clocks2h = 3 clocks… …Fh = 15 clocks

0


Lab 6: Analog-to-Digital Converter

Lab 6: Analog-to-Digital Converter Objective

The objective of this lab is to become familiar with the programming and operation of the on-chip analog-to-digital converter. The MCU will be setup to sample a single ADC input channel at a prescribed sampling rate and store the conversion result in a memory buffer. This buffer will operate in a circular fashion, such that new conversion data continuously overwrites older results in the buffer.

Lab 6: ADC Sampling

ADC

ADCINA0

RESULT0

...

datamemory

poin

ter

rew

ind

CPU copies resultto buffer duringADC ISR

ePWM2

ePWM2 triggeringADC on period match using SOCA trigger every 20 µs (50 kHz)

GND+3.3 V

(GPIO20)Toggle

(GPIO18)

connectorwire

View ADC buffer PWM Samples

Code ComposerStudio

Recall that there are three basic ways to initiate an ADC start of conversion (SOC): 1. Using software

a. SOCx bit (where x = 0 to 15) in the ADC SOC Force 1 Register (ADCSOCFRC1) causes a software initiated conversion

2. Automatically triggered on user selectable conditions a. CPU Timer 0/1/2 interrupt b. ePWMxSOCA / ePWMxSOCB (where x = 1 to 7)

- ePWM underflow (CTR = 0) - ePWM period match (CTR = PRD) - ePWM underflow or period match (CTR = 0 or PRD)

- ePWM compare match (CTRU/D = CMPA/B) c. ADC interrupt ADCINT1 or ADCINT2

- triggers SOCx (where x = 0 to 15) selected by the ADC Interrupt Trigger SOC Select1/2 Register (ADCINTSOCSEL1/2)

3. Externally triggered using a pin a. ADCSOC pin (GPIO/XINT2_ADCSOC)

One or more of these methods may be applicable to a particular application. In this lab, we will be using the ADC for data acquisition. Therefore, one of the ePWMs (ePWM2) will be



configured to automatically trigger the SOC A signal at the desired sampling rate (ePWM period match CTR = PRD SOC method 2b above). The ADC end-of-conversion interrupt will be used to prompt the CPU to copy the results of the ADC conversion into a results buffer in memory. This buffer pointer will be managed in a circular fashion, such that new conversion results will continuously overwrite older conversion results in the buffer. In order to generate an interesting input signal, the code also alternately toggles a GPIO pin (GPIO18) high and low in the ADC interrupt service routine. The ADC ISR will also toggle LED LD3 on the ControlCARD as a visual indication that the ISR is running. This pin will be connected to the ADC input pin, and sampled. After taking some data, Code Composer Studio will be used to plot the results. A flow chart of the code is shown in the following slide.

Lab 6: Code Flow Diagram

Start General Initialization• PLL and clocks• watchdog configure• GPIO setup• PIE initialization

ADC Initialization• convert channel A0 on

ePWM2 period match• send interrupt on

every conversion• setup a results buffer

in memory

ePWM2 Initialization• clear counter• set period register• set to trigger ADC onperiod match

• set the clock prescaler• enable the timer

Main Loopwhile(1){}

ADC ISR• read the ADC result• write to result buffer• adjust the buffer pointer• toggle the GPIO pin• return from interrupt

ADC interrupt

return

Notes • Program performs conversion on ADC channel A0 (ADCINA0 pin) • ADC conversion is set at a 50 kHz sampling rate • ePWM2 is triggering the ADC on period match using SOCA trigger • Data is continuously stored in a circular buffer • GPIO18 pin is also toggled in the ADC ISR • ADC ISR will also toggle the ControlCARD LED LD3 as a visual indication that it is

running



Procedure

Project File 1. A project named Lab6.pjt has been created for this lab. Open the project by clicking

on Project Open… and look in C:\C28x\Labs\Lab6. All Build Options have been configured the same as the previous lab. The files used in this lab are: Adc.c Gpio.cCodeStartBranch.asm Lab_5_6_7.cmdDefaultIsr_6.c Main_6.cDelayUs.asm PieCtrl_5_6_7_8_9_10.cDSP2803x_GlobalVariableDefs.c PieVect_5_6_7_8_9_10.cDSP2803x_Headers_nonBIOS.cmd SysCtrl.cEPwm_6.c Watchdog.c

Setup ADC Initialization and Enable Core/PIE Interrupts 2. In Main_6.c add code to call InitAdc() and InitEPwm() functions. The

InitEPwm() function is used to configure ePWM2 to trigger the ADC at a 50 kHz rate. Details about the ePWM and control peripherals will be discussed in the next module.

3. Edit Adc.c to implement the ADC initialization as described above in the objective for the lab. Configure SOC0 for single sample mode, with an acquisition sample window of 7 cycles. Don’t use the ADCINT to trigger a SOC0, and have all SOCs handled in round-robin mode. Enable ADCINT1 interrupt with EOC0 as the trigger for ADCINT1. Continuously generate an ADCINT1 pulse for each EOC.

4. Using the “PIE Interrupt Assignment Table” find the location for the ADC interrupt “ADCINT1” (high-priority) and fill in the following information:


This information will be used in the next step.

5. Modify the end of Adc.c to do the following: - Enable the "ADCINT" interrupt in the PIE (Hint: use the PieCtrlRegs structure) - Enable the appropriate core interrupt in the IER register

6. Open and inspect DefaultIsr_6.c. This file contains the ADC interrupt service routine.

Build and Load 7. Save all changes to the files and click the “Build” button.

8. Reset the CPU, select EMU_BOOT_SARAM, and then “Go Main”.



Run the Code 9. In Main_6.c place the cursor in the “main loop” section, right click on the mouse

key and select Run To Cursor.

10. Open a memory window to view some of the contents of the ADC results buffer. The address label for the ADC results buffer is AdcBuf.

Note: Exercise care when connecting any wires, as the power to the USB Docking Station is on, and we do not want to damage the ControlCARD!

11. Using a connector wire provided, connect the ADCINA0 (pin # ADC-A0) to “GND” (pin # GND) on the Docking Station. Then run the code again, and halt it after a few seconds. Verify that the ADC results buffer contains the expected value of 0x0000.

12. Adjust the connector wire to connect the ADCINA0 (pin # ADC-A0) to “+3.3V” (pin # GPIO-20) on the Docking Station. (Note: pin # GPIO-20 has been set to “1” in Gpio.c). Then run the code again, and halt it after a few seconds. Verify that the ADC results buffer contains the expected value of 0x0FFF.

13. Adjust the connector wire to connect the ADCINA0 (pin # ADC-A0) to GPIO18 (pin # GPIO-18) on the Docking Station. Then run the code again, and halt it after a few seconds. Examine the contents of the ADC results buffer (the contents should be alternating 0x0000 and 0x0FFF values). Are the contents what you expected?

14. Open and setup a graph to plot a 50-point window of the ADC results buffer. Click: View Graph Time/Frequency… and set the following values:

Start Address AdcBuf

Acquisition Buffer Size 50

Display Data Size 50

DSP Data Type 16-bit unsigned integer

Sampling Rate (Hz) 50000

Time Display Unit μs

Select OK to save the graph options.

15. Recall that the code toggled the GPIO18 pin alternately high and low. (Also, the ADC ISR is toggling the LED LD3 on the ControlCARD as a visual indication that the ISR is running). If you had an oscilloscope available to display GPIO18, you would expect to see a square-wave. Why does Code Composer Studio plot resemble a triangle wave? What is the signal processing term for what is happening here?



16. Recall that the program toggled the GPIO18 pin at a 50 kHz rate. Therefore, a complete cycle (toggle high, then toggle low) occurs at half this rate, or 25 kHz. We therefore expect the period of the waveform to be 40 μs. Confirm this by measuring the period of the triangle wave using the graph (you may want to enlarge the graph window using the mouse). The measurement is best done with the mouse. The lower left-hand corner of the graph window will display the X and Y axis values. Subtract the X-axis values taken over a complete waveform period.

Using Real-time Emulation Real-time emulation is a special emulation feature that offers two valuable capabilities:

A. Windows within Code Composer Studio can be updated at up to a 10 Hz rate while the MCU is running. This not only allows graphs and watch windows to update, but also allows the user to change values in watch or memory windows, and have those changes affect the MCU behavior. This is very useful when tuning control law parameters on-the-fly, for example.

B. It allows the user to halt the MCU and step through foreground tasks, while specified interrupts continue to get serviced in the background. This is useful when debugging portions of a realtime system (e.g., serial port receive code) while keeping critical parts of your system operating (e.g., commutation and current loops in motor control).

We will only be utilizing capability #1 above during the workshop. Capability #2 is a particularly advanced feature, and will not be covered in the workshop.

17. Reset the CPU, and then enable real-time mode by selecting:

Debug Real-time Mode

A message box may appear. Select YES to enable debug events. This will set bit 1 (DBGM bit) of status register 1 (ST1) to a “0”. The DBGM is the debug enable mask bit. When the DBGM bit is set to “0”, memory and register values can be passed to the host processor for updating the debugger windows.

18. The memory and graph windows displaying AdcBuf should still be open. The connector wire between ADCINA0 (pin # ADC-A0) and GPIO18 (pin # GPIO-18) should still be connected. In real-time mode, we would like to have our window continuously refresh. Click:

View Real-time Refresh Options…

and check “Global Continuous Refresh”. Use the default refresh rate of 100 ms and select OK. Alternately, we could have right clicked on each window individually and selected “Continuous Refresh”.



Note: “Global Continuous Refresh” causes all open windows to refresh at the refresh rate. This can be problematic when a large number of windows are open, as bandwidth over the emulation link is limited. Updating too many windows can cause the refresh frequency to bog down. In that case, either close some windows, or disable global refresh and selectively enable “Continuous Refresh” for individual windows of interest instead.

19. Run the code and watch the windows update in real-time mode. Carefully remove and replace the connector wire from GPIO18. Are the values updating as expected?

20. Fully halting the CPU when in real-time mode is a two-step process. First, halt the processor with Debug Halt. Then uncheck the “Real-time mode” to take the CPU out of real-time mode (Debug Real-time Mode).

21. So far, we have seen data flowing from the MCU to the debugger in realtime. In this step, we will flow data from the debugger to the MCU. • Open and inspect DefaultIsr_6.c. Notice that the global variable

DEBUG_TOGGLE is used to control the toggling of the GPIO18 pin. This is the pin being read with the ADC.

• Highlight DEBUG_TOGGLE with the mouse, right click and select “Add to Watch Window”. The global variable DEBUG_TOGGLE should now be in the watch window with a value of “1”.

• Run the code in real-time mode and change the value to “0”. Are the results shown in the memory and graph window as expected? Change the value back to “1”. As you can see, we are modifying data memory contents while the processor is running in real-time (i.e., we are not halting the MCU nor interfering with its operation in any way)! When done, fully halt the CPU.

22. Code Composer Studio includes GEL (General Extension Language) functions which automate entering and exiting real-time mode. Four functions are available: • Run_Realtime_with_Reset (reset CPU, enter real-time mode, run CPU) • Run_Realtime_with_Restart (restart CPU, enter real-time mode, run CPU) • Full_Halt (exit real-time mode, halt CPU) • Full_Halt_with_Reset (exit real-time mode, halt CPU, reset CPU) These GEL functions can be executed by clicking: GEL Realtime Emulation Control GEL Function In the remaining lab exercises we will be using the above GEL functions to run and halt the code in real-time mode. If you would like, try repeating the previous step using the following GEL functions: GEL Realtime Emulation Control Run_Realtime_with_Reset

GEL Realtime Emulation Control Full_Halt

End of Exercise


Control Peripherals

Introduction This module explains how to generate PWM waveforms using the ePWM unit. Also, the eCAP unit, and eQEP unit will be discussed.

Learning Objectives

Learning Objectives

Pulse Width Modulation (PWM) reviewGenerate a PWM waveform with the Pulse Width Modulator Module (ePWM)Use the Capture Module (eCAP) to measure the width of a waveformExplain the function of QuadratureEncoder Pulse Module (eQEP)

Note: Different numbers of ePWM, eCAP, and eQEP modules are available on F2803x and F2802x devices. See the device datasheet for more information.

C2000 Piccolo Workshop - Control Peripherals 7 - 1

Module Topics

Module Topics

Control Peripherals................................................................................................................................... 7-1

Module Topics......................................................................................................................................... 7-2 PWM Review........................................................................................................................................... 7-3 ePWM...................................................................................................................................................... 7-5

ePWM Time-Base Sub-Module ......................................................................................................... 7-6 ePWM Compare Sub-Module ............................................................................................................ 7-9 ePWM Action Qualifier Sub-Module................................................................................................7-11 Asymmetric and Symmetric Waveform Generation using the ePWM..............................................7-16 PWM Computation Example.............................................................................................................7-17 ePWM Dead-Band Sub-Module........................................................................................................7-18 ePWM PWM Chopper Sub-Module..................................................................................................7-21 ePWM Digital Compare Sub-Module ...............................................................................................7-24 ePWM Trip-Zone Sub-Module..........................................................................................................7-27 ePWM Event-Trigger Sub-Module ...................................................................................................7-30 Hi-Resolution PWM (HRPWM) .......................................................................................................7-33

eCAP ......................................................................................................................................................7-34 eQEP......................................................................................................................................................7-40 Lab 7: Control Peripherals....................................................................................................................7-42

7 - 2 C2000 Piccolo Workshop - Control Peripherals

PWM Review

PWM Review

What is Pulse Width Modulation?

PWM is a scheme to represent a signal as a sequence of pulses

fixed carrier frequencyfixed pulse amplitudepulse width proportional to instantaneous signal amplitudePWM energy ≈ original signal energy

t

Original SignalT

t

PWM representation

Pulse width modulation (PWM) is a method for representing an analog signal with a digital approximation. The PWM signal consists of a sequence of variable width, constant amplitude pulses which contain the same total energy as the original analog signal. This property is valuable in digital motor control as sinusoidal current (energy) can be delivered to the motor using PWM signals applied to the power converter. Although energy is input to the motor in discrete packets, the mechanical inertia of the rotor acts as a smoothing filter. Dynamic motor motion is therefore similar to having applied the sinusoidal currents directly.


PWM Review

Why use PWM with Power Switching Devices?

Desired output currents or voltages are knownPower switching devices are transistors

Difficult to control in proportional regionEasy to control in saturated region

PWM is a digital signal ⇒ easy for DSP to output

PWM approx.of desired signal

DC Supply

Desiredsignal tosystem

?DC Supply

Unknown Gate Signal Gate Signal Known with PWM

PWM


ePWM

ePWM ePWM Module Signals and Connections

ePWMx

ePWMx+1

EPWMxSYNCI

EPWMxSYNCO

PIEEPWMxINT

EPWMxTZINT

ePWMx-1

EPWMxSOCB

EPWMxSOCA

ADCCOMP COMPxOUT

EMUSTOP – TZ6

CLOCKFAIL – TZ5

EQEP1ERR – TZ4

CPU

SYSCTRL

eQEP1EPWMxA

EPWMxBGPIOMUX

TZ1 – TZ3GPIOMUX

ePWM Block Diagram

16-BitTime-Base

Counter

CompareLogic

ActionQualifier

DeadBand

PWMChopper

TripZone

Shadowed

CompareRegister

Shadowed

PeriodRegister

ClockPrescaler

Shadowed

CompareRegister

EPWMxA

EPWMxBSYSCLKOUTTZy

EPWMxSYNCI EPWMxSYNCO

TBCLK

DigitalCompare

TZ1-TZ3

COMPxOUT


ePWM

ePWM Time-Base Sub-Module

ePWM Time-Base Sub-Module

16-BitTime-Base

Counter

CompareLogic

ActionQualifier

DeadBand

PWMChopper

TripZone

Shadowed

CompareRegister

Shadowed

PeriodRegister

ClockPrescaler

Shadowed

CompareRegister

EPWMxA

EPWMxBSYSCLKOUTTZy


TBCLK

DigitalCompare

TZ1-TZ3

COMPxOUT

ePWM Time-Base Count ModesTBCTR

TBCTR

TBCTR

TBPRD

TBPRD

TBPRD

Count Up Mode

Count Down Mode

Count Up and Down Mode

AsymmetricalWaveform


SymmetricalWaveform


ePWM

ePWM Phase Synchronization

SyncIn

SyncOut

CTR=zeroCTR=CMPB

X

En

oo

o

oo

ooφ=120°Phase . EPWM2A

EPWM2B

SyncIn

SyncOut

CTR=zeroCTR=CMPB

X

En

oo

o

oo


EPWM3B

SyncIn

SyncOut

CTR=zeroCTR=CMPB

X

En

oo

o

oo


EPWM1B

φ=120°

φ=120°

φ=240°

Ext. SyncIn(optional)

To eCAP1SyncIn

ePWM Time-Base Sub-Module Registers(lab file: EPwm.c)

Name Description StructureTBCTL Time-Base Control EPwmxRegs.TBCTL.all =TBSTS Time-Base Status EPwmxRegs.TBSTS.all =TBPHS Time-Base Phase EPwmxRegs.TBPHS =TBCTR Time-Base Counter EPwmxRegs.TBCTR =TBPRD Time-Base Period EPwmxRegs.TBPRD =


ePWM

ePWM Time-Base Control RegisterEPwmxRegs.TBCTL

Upper Register:

FREE_SOFT PHSDIR CLKDIV HSPCLKDIV15 - 14 13 12 - 10 9 - 7

TBCLK = SYSCLKOUT / (HSPCLKDIV * CLKDIV)

TB Clock Prescale000 = /1 (default)001 = /2010 = /4011 = /8100 = /16101 = /32110 = /64111 = /128

High Speed TBClock Prescale000 = /1001 = /2 (default)010 = /4011 = /6100 = /8101 = /10110 = /12111 = /14

Emulation Halt Behavior00 = stop after next CTR inc/dec01 = stop when:

Up Mode; CTR = PRDDown Mode; CTR = 0Up/Down Mode; CTR = 0

1x = free run (do not stop)

Phase Direction0 = count down after sync1 = count up after sync

(HSPCLKDIV is for legacy compatibility)

ePWM Time-Base Control RegisterEPwmxRegs.TBCTL

Lower Register:

CTRMODESWFSYNC SYNCOSEL PRDLD PHSEN6 5 - 4 3 1 - 02

Software Force Sync Pulse0 = no action1 = force one-time sync

Sync Output Select(source of EPWMxSYNC0 signal)00 = EPWMxSYNCI01 = CTR = 010 = CTR = CMPB11 = disable SyncOut

Counter Mode00 = count up01 = count down10 = count up and down11 = stop – freeze (default)

Period Shadow Load0 = load on CTR = 01 = load immediately

Phase Reg. Enable0 = disable1 = CTR = TBPHS on

EPWMxSYNCI signal


ePWM

ePWM Compare Sub-Module

ePWM Compare Sub-Module

16-BitTime-Base

Counter

CompareLogic

ActionQualifier

DeadBand

PWMChopper

TripZone

Shadowed

CompareRegister

Shadowed

PeriodRegister

ClockPrescaler

Shadowed

CompareRegister

EPWMxA

EPWMxBSYSCLKOUTTZy


TBCLK

DigitalCompare

TZ1-TZ3

COMPxOUT

ePWM Compare Event WaveformsTBCTR

TBCTR

TBCTR

TBPRD

TBPRD

TBPRD

Count Up Mode

Count Down Mode

Count Up and Down Mode



SymmetricalWaveform

CMPA

CMPA

CMPA

CMPB

CMPB

CMPB

. . .. . .

. . . .. .

.. . . . .. .

. = compare events are fed to the Action Qualifier Sub-Module


ePWM

ePWM Compare Sub-Module Registers(lab file: EPwm.c)

Name Description StructureCMPCTL Compare Control EPwmxRegs.CMPCTL.all =CMPA Compare A EPwmxRegs.CMPA =CMPB Compare B EPwmxRegs.CMPB =

ePWM Compare Control RegisterEPwmxRegs.CMPCTL

6 5 4 1 - 0LOADBMODE LOADAMODEreserved

3 - 2SHDWBMODE SHDWAMODE

CMPA and CMPB Operating Mode0 = shadow mode;

double buffer w/ shadow register1 = immediate mode;

shadow register not used

CMPA and CMPB Shadow Load Mode00 = load on CTR = 001 = load on CTR = PRD10 = load on CTR = 0 or PRD11 = freeze (no load possible)

SHDWBFULL15 - 10 9 8

SHDWAFULL7

reservedreserved

CMPA and CMPB Shadow Full Flag(bit automatically clears on load)0 = shadow not full1 = shadow full


ePWM

ePWM Action Qualifier Sub-Module

ePWM Action Qualifier Sub-Module

16-BitTime-Base

Counter

CompareLogic

ActionQualifier

DeadBand

PWMChopper

TripZone

Shadowed

CompareRegister

Shadowed

PeriodRegister

ClockPrescaler

Shadowed

CompareRegister

EPWMxA

EPWMxBSYSCLKOUTTZy


TBCLK

DigitalCompare

TZ1-TZ3

COMPxOUT

ePWM Action Qualifier Actionsfor EPWMA and EPWMB

Z↓

Z↑

ZX

ZT

CA↓

CA↑

CAX

CAT

CB↓

CB↑

CBX

CBT

P↓

P↑

PX

PT

SW↓

SW↑

SWX

SWT

Do Nothing

Clear Low

Set High

Toggle

S/WForce

EPWMOutputActions

Time-Base Counter equals:

Zero CMPA CMPB TBPRD


ePWM

ePWM Count Up Asymmetric Waveformwith Independent Modulation on EPWMA / B

Z↑

PX

CBX

CA↓

Z↑

PX

CBX

CA↓

Z↑

PX

Z↑

PX

CB↓

CAX

Z↑

PX

CB↓

CAX

Z↑

PX

TBCTR

TBPRD

. . . .

EPWMA

EPWMB

ePWM Count Up Asymmetric Waveformwith Independent Modulation on EPWMA

CA↑

CB↓

CA↑

CB↓

ZT

ZT

ZT

TBCTR

TBPRD

. . . .

EPWMA

EPWMB


ePWM

ePWM Count Up-Down Symmetric Waveform

with Independent Modulation on EPWMA / BTBCTR

TBPRD .. .. .. . .

CA↑

CA↓

CA↑

CA↓

CB↑

CB↓

CB↑

CB↓

EPWMA

EPWMB

ePWM Count Up-Down Symmetric Waveform

with Independent Modulation on EPWMATBCTR

TBPRD

. .. .

CA↑

CB↓

CA↑

CB↓

Z↓

P↑

Z↓

P↑

EPWMA

EPWMB


ePWM

ePWM Action Qualifier Sub-Module Registers(lab file: EPwm.c)

Name Description StructureAQCTLA AQ Control Output A EPwmxRegs.AQCTLA.all =AQCTLB AQ Control Output B EPwmxRegs.AQCTLB.all =AQSFRC AQ S/W Force EPwmxRegs.AQSFRC.all =AQCSFRC AQ Cont. S/W Force EPwmxRegs.AQCSFRC.all =

ePWM Action Qualifier Control RegisterEPwmxRegs.AQCTLy (y = A or B)

ZROCBU CAD CAU PRD1 - 0

CBD15 - 12

reserved3 - 25 - 47 - 69 - 811 - 10

00 = do nothing (action disabled)01 = clear (low)10 = set (high)11 = toggle (low → high; high → low)

Action whenCTR = CMPB

on DOWN Count

Action whenCTR = CMPBon UP Count

Action whenCTR = CMPA

on DOWN Count

Action whenCTR = CMPAon UP Count

Action whenCTR = 0

Action whenCTR = PRD


ePWM

ePWM Action Qualifier S/W Force Register

EPwmxRegs.AQSFRC

ACTSFARLDCSF OTSFB ACTSFB OTSFA1 - 015 - 8

reserved24 - 357 - 6

AQSFRC Shadow Reload Options00 = load on event CTR = 001 = load on event CTR = PRD10 = load on event CTR = 0 or CTR = PRD11 = load immediately (from active reg.)

One-Time S/W Force on Output B / A0 = no action1 = single s/w force event

Action on One-Time S/W Force B / A00 = do nothing (action disabled)01 = clear (low)10 = set (high)11 = toggle (low → high; high → low)

ePWM Action Qualifier Continuous S/W Force Register

EPwmxRegs.AQCSFRC

CSFACSFB1 - 015 - 4

reserved3 - 2

Continuous S/W Force on Output B / A00 = forcing disabled01 = force continuous low on output10 = force continuous high on output11 = forcing disabled


ePWM

Asymmetric and Symmetric Waveform Generation using the ePWM PWM switching frequency: The PWM carrier frequency is determined by the value contained in the time-base period register, and the frequency of the clocking signal. The value needed in the period register is:

Asymmetric PWM: 1periodtimer

period switchingregister period −⎟⎟⎠

⎞⎜⎜⎝

⎛=

Symmetric PWM: period)2(timer

period switchingregister period =

Notice that in the symmetric case, the period value is half that of the asymmetric case. This is because for up/down counting, the actual timer period is twice that specified in the period register (i.e. the timer counts up to the period register value, and then counts back down).

PWM resolution: The PWM compare function resolution can be computed once the period register value is determined. The largest power of 2 is determined that is less than (or close to) the period value. As an example, if asymmetric was 1000, and symmetric was 500, then:

Asymmetric PWM: approx. 10 bit resolution since 210 = 1024 ≈ 1000

Symmetric PWM: approx. 9 bit resolution since 29 = 512 ≈ 500

PWM duty cycle: Duty cycle calculations are simple provided one remembers that the PWM signal is initially inactive during any particular timer period, and becomes active after the (first) compare match occurs. The timer compare register should be loaded with the value as follows:

Asymmetric PWM: TxCMPR TxPR cycle)duty - (100% = ∗

Symmetric PWM: TxPR cycle)duty - (100% = TxCMPR ∗

Note that for symmetric PWM, the desired duty cycle is only achieved if the compare registers contain the computed value for both the up-count compare and down-count compare portions of the time-base period.


ePWM

PWM Computation Example

Symmetric PWM Computation ExampleDetermine TBPRD and CMPA for 60 kHz, 25% duty symmetric PWM from a 60 MHz time base clock

CMPA = (100% - duty cycle)*TBPRD = 0.75*500 = 375

TBPRD = fTBCLKfPWM 22

1160 kHz60 MHz.. = 500=

Counter

Compare

Period

PWM PinfTBCLK = 60 MHz

CA↑

CA↓

fPWM = 60 kHz

..

Asymmetric PWM Computation ExampleDetermine TBPRD and CMPA for 60 kHz, 25% duty asymmetric PWM from a 60 MHz time base clock

CMPA = (100% - duty cycle)*(TBPRD+1) - 1 = 0.75*(999+1) - 1 = 749

TBPRD =fTBCLKfPWM 60 kHz

60 MHz - 1 = 999- 1 =

Counter

ComparePeriod

fPWM = 60 kHz

PWM Pin

P↓

CA↑

fTBCLK = 60 MHz

..


ePWM

ePWM Dead-Band Sub-Module

ePWM Dead-Band Sub-Module

16-BitTime-Base

Counter

CompareLogic

ActionQualifier

DeadBand

PWMChopper

TripZone

Shadowed

CompareRegister

Shadowed

PeriodRegister

ClockPrescaler

Shadowed

CompareRegister

EPWMxA

EPWMxBSYSCLKOUTTZy


TBCLK

DigitalCompare

TZ1-TZ3

COMPxOUT

Motivation for Dead-Band

to power switching device

supply rail

gate signals arecomplementary PWM

♦ Transistor gates turn on faster than they shut off♦ Short circuit if both gates are on at same time!


ePWM

Dead-band control provides a convenient means of combating current shoot-through problems in a power converter. Shoot-through occurs when both the upper and lower gates in the same phase of a power converter are open simultaneously. This condition shorts the power supply and results in a large current draw. Shoot-through problems occur because transistors open faster than they close, and because high-side and low-side power converter gates are typically switched in a complimentary fashion. Although the duration of the shoot-through current path is finite during PWM cycling, (i.e. the closing gate will eventually shut), even brief periods of a short circuit condition can produce excessive heating and over stress in the power converter and power supply.

ePWM Dead-Band Block Diagram

Rising Edge Delay

In Out(10-bit

counter)

Falling Edge Delay

In Out(10-bit

counter)

°° °0

1

°° °0

1

°° °0

1

°° °1

0°

°

.

.

.

.

PWMxA

PWMxB

PWMxB

PWMxAS1

S0

S2

S3 FED

RED

OUT-MODEPOLSEL

°° °0

1

°° °0

1

S4

S5

IN-MODEHALFCYCLE

Two basic approaches exist for controlling shoot-through: modify the transistors, or modify the PWM gate signals controlling the transistors. In the first case, the opening time of the transistor gate must be increased so that it (slightly) exceeds the closing time. One way to accomplish this is by adding a cluster of passive components such as resistors and diodes in series with the transistor gate, as shown in the next figure.

PWMsignal

R

by-pass diode

Shoot-through control via power circuit modification

The resistor acts to limit the current rise rate towards the gate during transistor opening, thus increasing the opening time. When closing the transistor however, current flows unimpeded from the gate via the by-pass diode and closing time is therefore not affected. While this passive approach offers an inexpensive solution that is independent of the control microprocessor, it is


ePWM

imprecise, the component parameters must be individually tailored to the power converter, and it cannot adapt to changing system conditions.

The second approach to shoot-through control separates transitions on complimentary PWM signals with a fixed period of time. This is called dead-band. While it is possible to perform software implementation of dead-band, the C28x offers on-chip hardware for this purpose that requires no additional CPU overhead. Compared to the passive approach, dead-band offers more precise control of gate timing requirements. In addition, the dead time is typically specified with a single program variable that is easily changed for different power converters or adapted on-line.

ePWM Dead-Band Sub-Module Registers(lab file: EPwm.c)

Rising Edge Delay = TTBCLK x DBRED Falling Edge Delay = TTBCLK x DBFED

Name Description StructureDBCTL Dead-Band Control EPwmxRegs.DBCTL.all =DBRED 10-bit Rising Edge Delay EPwmxRegs.DBRED =DBFED 10-bit Falling Edge Delay EPwmxRegs.DBFED =


ePWM

ePWM Dead Band Control RegisterEPwmxRegs.DBCTL

Polarity Select00 = active high01 = active low complementary (RED)10 = active high complementary (FED)11 = active low

Out-Mode Control00 = disabled (DBM bypass)01 = PWMxA = no delay

PWMxB = FED10 = PWMxA = RED

PWMxB = no delay11 = RED & FED (DBM fully enabled)

In-Mode Control00 = PWMxA is source for RED and FED01 = PWMxA is source for FED

PWMxB is source for RED10 = PWMxA is source for RED

PWMxB is source for FED11 = PWMxB is source for RED and FED

OUT_MODEPOLSEL1 - 014 - 6

reserved3 - 2

IN_MODE5 - 4

HALFCYCLE15

Half Cycle Clocking0 = full cycle clocking (TBCLK rate)1 = half cycle clocking (TBCLK*2 rate)

ePWM PWM Chopper Sub-Module

ePWM PWM Chopper Sub-Module

16-BitTime-Base

Counter

CompareLogic

ActionQualifier

DeadBand

PWMChopper

TripZone

Shadowed

CompareRegister

Shadowed

PeriodRegister

ClockPrescaler

Shadowed

CompareRegister

EPWMxA

EPWMxBSYSCLKOUTTZy


TBCLK

DigitalCompare

TZ1-TZ3

COMPxOUT


ePWM

Purpose of the PWM Chopper

Allows a high frequency carrier signal to modulate the PWM waveform generated by the Action Qualifier and Dead-Band modulesUsed with pulse transformer-based gate drivers to control power switching elements

ePWM Chopper WaveformEPWMxA

EPWMxB

CHPFREQ

EPWMxA

EPWMxB

OSHT

EPWMxA

ProgrammablePulse Width(OSHTWTH)

SustainingPulses

With One-Shot Pulse on EPWMxA and/or EPWMxB


ePWM

ePWM Chopper Sub-Module Registers(lab file: EPwm.c)

Name Description StructurePCCTL PWM-Chopper Control EPwmxRegs.PCCTL.all =

ePWM Chopper Control RegisterEPwmxRegs.PCCTL

CHPENCHPDUTY CHPFREQ OSHTWTH015 - 11

reserved

4 - 17 - 510 - 8

Chopper Enable0 = disable (bypass)1 = enable

One-Shot Pulse Width0000 = 1 x SYSCLKOUT/8 1000 = 9 x SYSCLKOUT/80001 = 2 x SYSCLKOUT/8 1001 = 10 x SYSCLKOUT/80010 = 3 x SYSCLKOUT/8 1010 = 11 x SYSCLKOUT/80011 = 4 x SYSCLKOUT/8 1011 = 12 x SYSCLKOUT/80100 = 5 x SYSCLKOUT/8 1100 = 13 x SYSCLKOUT/80101 = 6 x SYSCLKOUT/8 1101 = 14 x SYSCLKOUT/80110 = 7 x SYSCLKOUT/8 1110 = 15 x SYSCLKOUT/80111 = 8 x SYSCLKOUT/8 1111 = 16 x SYSCLKOUT/8

Chopper Clk Freq.000 = SYSCLKOUT/8 ÷ 1001 = SYSCLKOUT/8 ÷ 2010 = SYSCLKOUT/8 ÷ 3011 = SYSCLKOUT/8 ÷ 4100 = SYSCLKOUT/8 ÷ 5101 = SYSCLKOUT/8 ÷ 6110 = SYSCLKOUT/8 ÷ 7111 = SYSCLKOUT/8 ÷ 8

Chopper Clk Duty Cycle000 = 1/8 (12.5%)001 = 2/8 (25.0%)010 = 3/8 (37.5%)011 = 4/8 (50.0%)100 = 5/8 (62.5%)101 = 6/8 (75.0%)110 = 7/8 (87.5%)111 = reserved


ePWM

ePWM Digital Compare Sub-Module

ePWM Digital Compare Sub-Module

16-BitTime-Base

Counter

CompareLogic

ActionQualifier

DeadBand

PWMChopper

TripZone

Shadowed

CompareRegister

Shadowed

PeriodRegister

ClockPrescaler

Shadowed

CompareRegister

EPWMxA

EPWMxBSYSCLKOUTTZy


TBCLK

DigitalCompare

TZ1-TZ3

COMPxOUT

Purpose of the Digital CompareSub-Module

Comparator module outputs (COMP1, COMP2, and COMP3) and Trip-Zone inputs (TZ1, TZ2, and TZ3)generate Digital Compare A and B High/Low Signals (DCAH, DCAL, DCBH, and DCBL)

DCAH/L and DCBH/L signals trigger events which can be filtered or fed directly to the trip-zone, event-trigger, and time-base sub-modules to:

Generate a trip-zone interruptGenerate an ADC start of conversionForce an eventGenerate a synchronization event for synchronizing the ePWM module TBCNT

Event filtering can optionally blank the input signal to remove noise


ePWM

Digital Compare Sub-Module Signals

The Digital Compare sub-module compares signals external to the ePWM module to directly generate events which are then feed to the Event-Trigger, Trip-Zone, and Time-Base sub-modules

TZ1

TZ2

TZ3

COMP1OUT

COMP2OUT

COMP3OUT

Digital TripEvent A1Compare

Digital TripEvent A2Compare

Digital TripEvent B1Compare

Digital TripEvent B2Compare

Generate PWM SyncTime-Base Sub-Module

Generate SOCAEvent-Trigger Sub-Module

Trip PWMA OutputGenerate Trip Interrupt

Trip-Zone Sub-Module

Generate PWM SyncTime-Base Sub-Module

Generate SOCBEvent-Trigger Sub-Module

Trip PWMB OutputGenerate Trip Interrupt

Trip-Zone Sub-Module

DCAH

DCAL

DCBH

DCBL

DCTRIPSEL TZDCSEL DCACTRL / DCBCTRL

ePWM Digital Compare Sub-Module Registers(lab file: EPwm.c)

Name Description StructureDCACTL DC A Control EPwmxRegs.DCACTL.all =DCBCTL DC B Control EPwmxRegs.DCBCTL.all =DCTRIPSEL DC Trip Select EPwmxRegs.DCTRIPSEL.all =DCCAPCTL Capture Control EPWMxRegs.DCCAPCTL.all =DCCAP Counter Capture EPwmxRegs.DCCAP =DCFCTL DC Filter Control EPwmxRegs.DCFCTL.all =DCFOFFSETCNT Filter Offset Ctr EPwmxRegs.DCOFFSETCNT =DCFWINDOW Filter Window EPwmxRegs.DCFWINDOW =DCFWINDOWCNT Filter Window Ctr EPwmxRegs.DCFWINDOWCNT =


ePWM

ePWM Digital Compare Control RegisterEPwmxRegs.DCyCTL (y = A or B)

9 8 2 0reserved

17 - 415 - 10EVT1FRCSYNCSEL

EVT2FRCSYNCSEL

EVT2SRCSEL

EVT1SRCSEL

EVT1SYNCE

EVT1SOCEreserved

3

DCyEVT1 SourceSignal Select0 = DCyEVT1 signal1 = DCEVTFILT signal

DCyEVT2 SourceSignal Select0 = DCyEVT2 signal1 = DCEVTFILT signal

DCyEVT1 Source ForceSync Signal Select0 = synchronous1 = asynchronous

DCyEVT1 SOCGeneration0 = disable1 = enable

DCyEVT1 SYNCGeneration0 = disable1 = enable

DCyEVT2 Source ForceSync Signal Select0 = synchronous1 = asynchronous

ePWM Digital Compare Trip Select Register

EPwmxRegs.DCTRIPSEL

DCBLCOMPSEL15 - 12 11 - 8

7 - 4 3 - 0

DCBHCOMPSEL

DCALCOMPSEL DCAHCOMPSEL

Digital Compare BLow Input Source Select

Digital Compare BHigh Input Source Select

Digital Compare ALow Input Source Select

Digital Compare AHigh Input Source Select

0000 = TZ1 input0001 = TZ2 input0010 = TZ3 input1000 = COMP1OUT input1001 = COMP2OUT input1010 = COMP3OUT inputother values reserved


ePWM

ePWM Trip-Zone Sub-Module

ePWM Trip-Zone Sub-Module

16-BitTime-Base

Counter

CompareLogic

ActionQualifier

DeadBand

PWMChopper

TripZone

Shadowed

CompareRegister

Shadowed

PeriodRegister

ClockPrescaler

Shadowed

CompareRegister

EPWMxA

EPWMxBSYSCLKOUTTZy


TBCLK

DigitalCompare

TZ1-TZ3

COMPxOUT

Trip-Zone Features♦ Trip-Zone has a fast, clock independent logic path to high-impedance

the EPWMxA/B output pins♦ Interrupt latency may not protect hardware when responding to over

current conditions or short-circuits through ISR software♦ Supports: #1) one-shot trip for major short circuits or over

current conditions#2) cycle-by-cycle trip for current limiting operation

CPUcore P

WM

OUTPUTS

EPWMxTZINT

EPWM1A

TZ6TZ5TZ4TZ3TZ2TZ1

OverCurrentSensors

Cycle-by-CycleMode

One-ShotMode

EPWM1B

EPWMxAEPWMxB

COMPxOUT DigitalCompare

CPUSYSCTRL

eQEP1

•••

EMUSTOPCLOCKFAILEQEP1ERR

The power drive protection is a safety feature that is provided for the safe operation of systems such as power converters and motor drives. It can be used to inform the monitoring program of


ePWM

motor drive abnormalities such as over-voltage, over-current, and excessive temperature rise. If the power drive protection interrupt is unmasked, the PWM output pins will be put in the high-impedance state immediately after the pin is driven low. An interrupt will also be generated.

ePWM Trip-Zone Sub-Module Registers(lab file: EPwm.c)

Name Description StructureTZCTL Trip-Zone Control EPwmxRegs.TZCTL.all =TZSEL Trip-Zone Select EPwmxRegs.TZSEL.all =TZEINT Enable Interrupt EPwmxRegs.TZEINT.all =TZDCSEL Digital Compare EPWMxRegs.TZDCSEL.all =TZFLG Trip-Zone Flag EPwmxRegs.TZFLG.all =TZCLR Trip-Zone Clear EPwmxRegs.TZCLR.all =TZFRC Trip-Zone Force EPwmxRegs.TZFRC.all =

ePWM Trip-Zone Control RegisterEPwmxRegs.TZCTL

TZATZB1 - 015 - 12

reserved

3 - 2

TZ1 to TZ6 Action onEPWMxB / EPWMxA

DCBEVT2 DCBEVT1 DCAEVT2 DCAEVT15 - 47 - 69 - 811 - 10

00 = high impedance01 = force high10 = force low11 = do nothing (disable)

Digital Compare OutputEvent 2 / 1 Action

on EPWMxA

Digital Compare OutputEvent 2 / 1 Action

on EPWMxB


ePWM

ePWM Trip-Zone Select RegisterEPwmxRegs.TZSEL

OSHT1OSHT5 OSHT4 OSHT3 OSHT28

OSHT615 910111213

CBC1CBC5 CBC4 CBC3 CBC20

CBC67 12345

Cycle-by-Cycle Trip Zone(event cleared when CTR = 0;i.e. cleared every PWM cycle)0 = disable as trip source1 = enable as trip source

One-Shot Trip Zone(event only cleared under S/Wcontrol; remains latched)0 = disable as trip source1 = enable as trip source

14

6

DCBEVT1

DCBEVT2 DCAEVT2

DCAEVT1

ePWM Trip-Zone Enable Interrupt Register

EPwmxRegs.TZEINT

OST CBCreserved15 - 7 02 1

reserved

Cycle-by-CycleInterrupt Enable0 = disable1 = enable

One-ShotInterrupt Enable0 = disable1 = enable

DCBEVT2 DCBEVT1 DCAEVT2 DCAEVT1

Digital CompareOutput B Event 2 / 1 Enable0 = disable1 = enable

Digital CompareOutput A Event 2 / 1 Enable0 = disable1 = enable

3456


ePWM

ePWM Trip-Zone Digital Compare Event Select Register

EPwmxRegs.TZDCSEL

2 - 015 - 12

reserved

5 - 3DCBEVT2 DCBEVT1 DCAEVT2 DCAEVT1

8 - 611 - 9

000 = event disable001 = DCBH low, DCBL don’t care010 = DCBH high, DCBL don’t care011 = DCBL low, DCBH don’t care100 = DCBL high, DCBH don’t care101 = DCBL high, DCBH low11x = reserved

Digital Compare Output AEvent 2 / 1 Select

Digital Compare Output BEvent 2 / 1 Select

ePWM Event-Trigger Sub-Module

ePWM Event-Trigger Sub-Module

16-BitTime-Base

Counter

CompareLogic

ActionQualifier

DeadBand

PWMChopper

TripZone

Shadowed

CompareRegister

Shadowed

PeriodRegister

ClockPrescaler

Shadowed

CompareRegister

EPWMxA

EPWMxBSYSCLKOUTTZy


TBCLK

DigitalCompare

TZ1-TZ3

COMPxOUT


ePWM

ePWM Event-Trigger Interrupts and SOCTBCTRTBPRD .. .. .. . .

EPWMA

EPWMB

CMPBCMPA

CTR = 0

CTR = PRD

CTRU = CMPA

CTRD = CMPA

CTRU = CMPB

CTRD = CMPB

CTR = 0 or PRD

ePWM Event-Trigger Sub-Module Registers(lab file: EPwm.c)

Name Description StructureETSEL Event-Trigger Selection EPwmxRegs.ETSEL.all =ETPS Event-Trigger Pre-Scale EPwmxRegs.ETPS.all =ETFLG Event-Trigger Flag EPwmxRegs.ETFLG.all =ETCLR Event-Trigger Clear EPwmxRegs.ETCLR.all =ETFRC Event-Trigger Force EPwmxRegs.ETFRC.all =


ePWM

ePWM Event-Trigger Selection RegisterEPwmxRegs.ETSEL

15 11 7 - 4 2 - 0INTEN INTSELreserved

3SOCBSEL SOCASELSOCAENSOCBEN

10 - 814 - 12

Enable SOCB / A0 = disable1 = enable

EPWMxSOCB / A Select000 = DCBEVT1 / DCAEVT1001 = CTR = 0010 = CTR = PRD011 = CTR = 0 or PRD100 = CTRU = CMPA101 = CTRD = CMPA110 = CTRU = CMPB111 = CTRD = CMPB

Enable EPWMxINT0 = disable1 = enable

EPWMxINT Select000 = reserved001 = CTR = 0010 = CTR = PRD011 = CTR = 0 or PRD100 = CTRU = CMPA101 = CTRD = CMPA110 = CTRU = CMPB111 = CTRD = CMPB

ePWM Event-Trigger Prescale RegisterEPwmxRegs.ETPS

15 - 14 11 - 10 7 - 4 1 - 0INTCNT INTPRDreserved

2 - 3SOCBPRD SOCAPRDSOCACNTSOCBCNT

9 - 813 - 12

EPWMxSOCB / A Counter(number of events have occurred)00 = no events01 = 1 event10 = 2 events11 = 3 events

EPWMxSOCB / A Period(number of events before SOC)00 = disabled01 = SOC on first event10 = SOC on second event11 = SOC on third event

EPWMxINT Counter(number of events have occurred)00 = no events01 = 1 event10 = 2 events11 = 3 events

EPWMxINT Period(number of events before INT)00 = disabled01 = INT on first event10 = INT on second event11 = INT on third event


ePWM

Hi-Resolution PWM (HRPWM)

Hi-Resolution PWM (HRPWM)

Significantly increases the resolution of conventionally derived digital PWMUses 8-bit extensions to Compare registers (CMPxHR), Period register (TBPRDHR) and Phase register (TBPHSHR) for edge positioning controlTypically used when PWM resolution falls below ~9-10 bits which occurs at frequencies greater than ~120 kHz (with system clock of 60 MHz)Not all ePWM outputs support HRPWM feature (see device datasheet)

PWM Period

Device Clock(i.e. 60 MHz)

Regular PWM Step

(i.e. 16.67 ns)

HRPWM Micro Step (~150 ps)

HRPWM divides a clock cycle into smaller steps

called Micro Steps(Step Size ~= 150 ps)

ms ms ms ms ms ms

Calibration Logic

Calibration Logic tracks the number of Micro Steps per

clock to account for variations caused by Temp/Volt/Process


eCAP

eCAP Capture Module (eCAP)

The eCAP module timestamps transitions on a capture input pin

Timer

TimestampValues

Trigger

pin

The capture units allow time-based logging of external TTL signal transitions on the capture input pins. The C28x has up to six capture units.

Capture units can be configured to trigger an A/D conversion that is synchronized with an external event. There are several potential advantages to using the capture for this function over the ADCSOC pin associated with the ADC module. First, the ADCSOC pin is level triggered, and therefore only low to high external signal transitions can start a conversion. The capture unit does not suffer from this limitation since it is edge triggered and can be configured to start a conversion on either rising edges or falling edges. Second, if the ADCSOC pin is held high longer than one conversion period, a second conversion will be immediately initiated upon completion of the first. This unwanted second conversion could still be in progress when a desired conversion is needed. In addition, if the end-of-conversion ADC interrupt is enabled, this second conversion will trigger an unwanted interrupt upon its completion. These two problems are not a concern with the capture unit. Finally, the capture unit can send an interrupt request to the CPU while it simultaneously initiates the A/D conversion. This can yield a time savings when computations are driven by an external event since the interrupt allows preliminary calculations to begin at the start-of-conversion, rather than at the end-of-conversion using the ADC end-of-conversion interrupt. The ADCSOC pin does not offer a start-of-conversion interrupt. Rather, polling of the ADCSOC bit in the control register would need to be performed to trap the externally initiated start of conversion.


eCAP

Some Uses for the Capture Module

Problem: At low speeds, calculation of speed based on a measured position change at fixed time intervals produces large estimate errors

Alternative: Estimate the speed using a measured time interval at fixed position intervals

Signal from onequadratureencoder channel

Low speed velocity estimation from incr. encoder:Measure the time width of a pulse

vk ≈ Δxtk - tk-1

vk ≈Δt

xk - xk-1

Δx

Auxiliary PWM generation

eCAP Module Block Diagram – Capture Mode

32-BitTime-Stamp

Counter

Capture 1Register

EventPrescale

PolaritySelect 1

PolaritySelect 2

PolaritySelect 3

PolaritySelect 4

Capture 2Register

Capture 3Register

Capture 4Register

Even

t Log

ic

ECAPxpin

SYSCLKOUT

CAP1POL

CAP2POL

CAP3POL

CAP4POL

PRESCALE


eCAP

eCAP Module Block Diagram – APWM Mode

32-BitTime-Stamp

Counter

PeriodRegister

(CAP3)Period

Register(CAP1)

CompareRegister

(CAP4)

CompareRegister(CAP2)

PWMCompare

Logic ECAPpin

Shadowed

Shadowed

SYSCLKOUT

immediatemode

shadowmode

shadowmode

immediatemode

eCAP Module Registers(lab file: ECap.c)

Name Description StructureECCTL1 Capture Control 1 ECapxRegs.ECCTL1.all =ECCTL2 Capture Control 2 ECapxRegs.ECCTL2.all =TSCTR Time-Stamp Counter ECapxRegs.TSCTR =CTRPHS Counter Phase Offset ECapxRegs.CTRPHS =CAP1 Capture 1 ECapxRegs.CAP1 =CAP2 Capture 2 ECapxRegs.CAP2 =CAP3 Capture 3 ECapxRegs.CAP3 =CAP4 Capture 4 ECapxRegs.CAP4 =ECEINT Enable Interrupt ECapxRegs.ECEINT.all =ECFLG Interrupt Flag ECapxRegs.ECFLG.all =ECCLR Interrupt Clear ECapxRegs.ECCLR.all =ECFRC Interrupt Force ECapxRegs.ECFRC.all =


eCAP

eCAP Control Register 1ECapxRegs.ECCTL1

CAPLDENFREE_SOFT PRESCALE15 - 14 13 - 9 8

Upper Register:

Emulation Control00 = TSCTR stops immediately01 = TSCTR runs until equals 01X = free run (do not stop)

Event Filter Prescale Counter00000 = divide by 1 (bypass)00001 = divide by 200010 = divide by 400011 = divide by 600100 = divide by 8

11110 = divide by 6011111 = divide by 62

CAP1 – 4 Loadon Capture Event0 = disable1 = enable


Lower Register:

CTRRST4 CAP4POL7 3 2

CTRRST3 CAP3POL CTRRST2 CAP2POL CTRRST1 CAP1POL01456

Counter Reset on Capture Event0 = no reset (absolute time stamp mode)1 = reset after capture (difference mode)

Capture Event Polarity0 = trigger on rising edge1 = trigger on falling edge


eCAP


Upper Register:

SWSYNCAPWMPOL CAP_APWM

10 815 - 11

reserved

9

APWM Output Polarity(valid only in APWM mode)0 = active high output1 = active low output

Capture / APWM mode0 = capture mode1 = APWM mode

Software ForceCounter Synchronization0 = no effect1 = TSCTR load of current

module and other modulesif SYNCO_SEL bits = 00


Lower Register:

SYNCO_SEL SYNCI_EN

7 - 6 3 02 - 1

TSCTRSTOP REARM STOP_WRAP CONT_ONESHT

45

Sync-Out Select00 = sync-in to sync-out01 = CTR = PRD event

generates sync-out1X = disable

Counter Sync-In0 = disable1 = enable

Time StampCounter Stop0 = stop1 = run

Re-arm(capture mode only)0 = no effect1 = arm sequence

Stop Value for One-Shot Mode/Wrap Value for Continuous Mode(capture mode only)00 = stop/wrap after capture event 101 = stop/wrap after capture event 210 = stop/wrap after capture event 311 = stop/wrap after capture event 4

Continuous/One-Shot(capture mode only)0 = continuous mode1 = one-shot mode


eCAP

The capture unit interrupts offer immediate CPU notification of externally captured events. In situations where this is not required, the interrupts can be masked and flag testing/polling can be used instead. This offers increased flexibility for resource management. For example, consider a servo application where a capture unit is being used for low-speed velocity estimation via a pulsing sensor. The velocity estimate is not used until the next control law calculation is made, which is driven in real-time using a timer interrupt. Upon entering the timer interrupt service routine, software can test the capture interrupt flag bit. If sufficient servo motion has occurred since the last control law calculation, the capture interrupt flag will be set and software can proceed to compute a new velocity estimate. If the flag is not set, then sufficient motion has not occurred and some alternate action would be taken for updating the velocity estimate. As a second example, consider the case where two successive captures are needed before a computation proceeds (e.g. measuring the width of a pulse). If the width of the pulse is needed as soon as the pulse ends, then the capture interrupt is the best option. However, the capture interrupt will occur after each of the two captures, the first of which will waste a small number of cycles while the CPU is interrupted and then determines that it is indeed only the first capture. If the width of the pulse is not needed as soon as the pulse ends, the CPU can check, as needed, the capture registers to see if two captures have occurred, and proceed from there.

eCAP Interrupt Enable RegisterECapxRegs.ECEINT

CTR=CMP CTR=PRD7 3 2

CTROVF CEVT4 CEVT3 CEVT2 CEVT101456

reserved15 - 8

reserved

0 = disable as interrupt source1 = enable as interrupt source

CTR = CMPInterrupt Enable

CTR = PRDInterrupt Enable

CTR = OverflowInterrupt Enable

Capture Event 3Interrupt Enable





eQEP

eQEP

What is an Incremental QuadratureEncoder?

A digital (angular) position sensor

slots spaced θ deg. apart

photo sensors spaced θ/4 deg. apart

light source (LED)

shaft rotation

Ch. A

Ch. B

Quadrature Output from Photo Sensors

θ

θ/4

Incremental Optical Encoder

The eQEP circuit, when enabled, decodes and counts the quadrature encoded input pulses. The QEP circuit can be used to interface with an optical encoder to get position and speed information from a rotating machine.

How is Position Determined from Quadrature Signals?

Ch. A

Ch. B

(00) (11)(10) (01)(A,B) =

00

01

11

10

Quadrature DecoderState Machine

incrementcounter

decrementcounter

Position resolution is θ/4 degrees

Illegal Transitions;

generate phase error

interrupt


eQEP

eQEP Module Block Diagram

QuadratureDecoder

EQEPxA/XCLK

EQEPxB/XDIR

EQEPxI

EQEPxS

Position/CounterCompare

QuadratureCapture

32-Bit UnitTime-Base

QEPWatchdog

SYSCLKOUT

Generate the direction and clock for the position counter in quadrature count modeGenerate a sync output

and/or interrupt on a position compare match

Measure the elapsed time between the unit position events; used for low speed measurement

Generate periodic interrupts for velocity calculations

Monitors the quadratureclock to indicate proper operation of the motion control system

Quadrature -clock mode

Direction -count mode

eQEP Module Connections

Ch. A

Ch. B

IndexQuadrature

Decoder

EQEPxA/XCLK

EQEPxB/XDIR

EQEPxI

EQEPxS

Position/CounterCompare

QuadratureCapture

32-Bit UnitTime-Base

QEPWatchdog

SYSCL KOUT

Strobefrom homing sensor


Lab 7: Control Peripherals

Lab 7: Control Peripherals Objective

The objective of this lab is to become familiar with the programming and operation of the control peripherals and their interrupts. ePWM1A will be setup to generate a 2 kHz, 25% duty cycle symmetric PWM waveform. The waveform will then be sampled with the on-chip analog-to-digital converter and displayed using the graphing feature of Code Composer Studio. Next, eCAP1 will be setup to detect the rising and falling edges of the waveform. This information will be used to determine the width of the pulse and duty cycle of the waveform. The results of this step will be viewed numerically in a memory window.


ADCRESULT0

...

datamemory

poin

ter

rew

ind

CPU copiesresult tobuffer duringADC ISR

ePWM2

connectorwire

Capture 1 RegisterADC-INA0

TB CounterCompare

Action Qualifier

ePWM1

eCAP1

Capture 2 Register

Capture 3 Register

Capture 4 RegisterView ADC buffer PWM Samples

Code ComposerStudio


Procedure


on Project Open… and look in C:\C28x\Labs\Lab7. All Build Options have been configured the same as the previous lab. The files used in this lab are: Adc.c Gpio.cCodeStartBranch.asm Lab_5_6_7.cmdDefaultIsr_7.c Main_7.cDelayUs.asm PieCtrl_5_6_7_8_9_10.cDSP2833x_GlobalVariableDefs.c PieVect_5_6_7_8_9_10.cDSP2833x_Headers_nonBIOS.cmd SysCtrl.cECap_7_8_9_10_12.c Watchdog.cEPwm_7_8_9_10_12.c



Setup Shared I/O and ePWM1 2. Edit Gpio.c and adjust the shared I/O pin in GPIO0 for the PWM1A function.

3. In EPwm_7_8_9_10_12.c, setup ePWM1 to implement the PWM waveform as described in the objective for this lab. The following registers need to be modified: TBCTL (set clock prescales to divide-by-1, no software force, sync and phase disabled), TBPRD, CMPA, CMPCTL (load on 0 or PRD), and AQCTLA (set on up count and clear on down count for output A). Software force, deadband, PWM chopper and trip action has been disabled. (Hint – notice the last steps enable the timer count mode and enable the clock to the ePWM module). Either calculate the values for TBPRD and CMPA (as a challenge) or make use of the global variable names and values that have been set using #define in the beginning of Lab.h file. Notice that ePWM2 has been initialized earlier in the code for the ADC lab. Save your work.

Build and Load 4. Save all changes to the files and click the “Build” button to build and load the project.

Run the Code – PWM Waveform 5. Open a memory window to view some of the contents of the ADC results buffer. The

address label for the ADC results buffer is AdcBuf. We will be running our code in real-time mode, and will have our window continuously refresh.

6. Using a connector wire provided, connect the PWM1A (pin # GPIO-00) to ADCINA0 (pin # ADC-A0) on the Docking Station.

7. Run the code (real-time mode) using the GEL function: GEL Realtime Emulation Control Run_Realtime_with_Reset. Watch the window update. Verify that the ADC result buffer contains the updated values.

8. Open and setup a graph to plot a 50-point window of the ADC results buffer. Click: View Graph Time/Frequency… and set the following values:










9. The graphical display should show the generated 2 kHz, 25% duty cycle symmetric PWM waveform. The period of a 2 kHz signal is 500 μs. You can confirm this by measuring the period of the waveform using the graph (you may want to enlarge the graph window using the mouse). The measurement is best done with the mouse. The lower left-hand corner of the graph window will display the X and Y-axis values. Subtract the X-axis values taken over a complete waveform period (you can use the PC calculator program found in Microsoft Windows to do this).

Frequency Domain Graphing Feature of Code Composer Studio 10. Code Composer Studio also has the ability to make frequency domain plots. It does this

by using the PC to perform a Fast Fourier Transform (FFT) of the DSP data. Let's make a frequency domain plot of the contents in the ADC results buffer (i.e. the PWM waveform).

Click: View Graph Time/Frequency… and set the following values:

Display Type FFT Magnitude



FFT Framesize 50




11. On the plot window, left-click the mouse to move the vertical marker line and observe the frequencies of the different magnitude peaks. Do the peaks occur at the expected frequencies?

12. Fully halt the CPU (real-time mode) by using the GEL function: GEL Realtime Emulation Control Full_Halt.

Setup eCAP1 to Measure Width of Pulse The first part of this lab exercise generated a 2 kHz, 25% duty cycle symmetric PWM waveform which was sampled with the on-chip analog-to-digital converter and displayed using the graphing feature of Code Composer Studio. Next, eCAP1 will be setup to detect the rising and falling edges of the waveform. This information will be used to determine the period and duty cycle of the waveform. The results of this step will be viewed numerically in a memory window and can be compared to the results obtained using the graphing features of Code Composer Studio.

13. Add the following file to the project:

ECap_7_8_9_10_12.c



Check your files list to make sure the file is there.

14. In Main_7.c, add code to call the InitECap() function. There are no passed parameters or return values, so the call code is simply:

InitECap();

15. Edit Gpio.c and adjust the shared I/O pin in GPIO5 for the ECAP1 function.

16. Open and inspect the eCAP1 interrupt service routine (ECAP1_INT_ISR) in the file DefaultIsr_7.c. Notice that PwmDuty is calculated by CAP2 – CAP1 (rising to falling edge) and that PwmPeriod is calculated by CAP3 – CAP1 (rising to rising edge).

17. In ECap_7_8_9_10_12.c, setup eCAP1 to calculate PWM_duty and PWM_period. The following registers need to be modified: ECCTL2 (continuous mode, re-arm disable, and sync disable), ECCTL1 (set prescale to divide-by-1, configure capture event polarity without reseting the counter), and ECEINT (enable desired eCAP interrupt).

18. Using the “PIE Interrupt Assignment Table” find the location for the eCAP1 interrupt “ECAP1_INT” and fill in the following information:



19. Modify the end of ECap_7_8_9_10_12.c to do the following: - Enable the “ECAP1_INT” interrupt in the PIE (Hint: use the PieCtrlRegs structure) - Enable the appropriate core interrupt in the IER register

Build and Load 20. Save all changes to the files and click the “Build” button.

Run the Code – Pulse Width Measurement 21. Open a memory window to view the address label PwmPeriod. (Type &PwmPeriod in

the address box). The address label PwmDuty (address &PwmDuty) should appear in the same memory window.

22. Set the memory window properties format to “32-Bit UnSigned Int”.

23. Using the connector wire provided, connect the PWM1A (pin # GPIO-00) to ECAP1 (pin # GPIO-05) on the Docking Station.

24. Run the code (real-time mode) by using the GEL function: GEL Realtime Emulation Control Run_Realtime_with_Reset. Notice the values for PwmDuty and PwmPeriod.




Questions: • How do the captured values for PwmDuty and PwmPeriod relate to the compare register

CMPA and time-base period TBPRD settings for ePWM1A? • What is the value of PwmDuty in memory? • What is the value of PwmPeriod in memory? • How does it compare with the expected value?

End of Exercise


Numerical Concepts

Introduction In this module, numerical concepts will be explored. One of the first considerations concerns multiplication – how does the user store the results of a multiplication, when the process of mul-tiplication creates results larger than the inputs. A similar concern arises when considering accu-mulation – especially when long summations are performed. Next, floating-point concepts will be explored and IQmath will be described as a technique for implementing a “virtual floating-point” system to simplify the design process.

The IQmath Library is a collection of highly optimized and high precision mathematical functions used to seamlessly port floating-point algorithms into fixed-point code. These C/C++ routines are typically used in computationally intensive real-time applications where optimal execution speed and high accuracy is needed. By using these routines a user can achieve execution speeds considerable faster than equivalent code written in standard ANSI C language. In addition, by incorporating the ready-to-use high precision functions, the IQmath library can shorten significantly a DSP application development time. (The IQmath user's guide is included in the application zip file, and can be found in the /docs folder once the file is extracted and installed).


Integers and FractionsIEEE-754 Floating-PointIQmathFormat Conversion of ADC Results

C2000 Piccolo Workshop - Numerical Concepts 8 - 1

Module Topics

Module Topics Numerical Concepts .................................................................................................................................. 8-1

Module Topics......................................................................................................................................... 8-2 Numbering System Basics ....................................................................................................................... 8-3

Binary Numbers.................................................................................................................................. 8-3 Two's Complement Numbers ............................................................................................................. 8-3 Integer Basics ..................................................................................................................................... 8-4 Sign Extension Mode.......................................................................................................................... 8-5

Binary Multiplication.............................................................................................................................. 8-6 Binary Fractions ..................................................................................................................................... 8-8

Representing Fractions in Binary ....................................................................................................... 8-8 Fraction Basics ................................................................................................................................... 8-8 Multiplying Binary Fractions ............................................................................................................. 8-9

Fraction Coding.....................................................................................................................................8-11 Fractional vs. Integer Representation....................................................................................................8-12 Floating-Point........................................................................................................................................8-13 IQmath ...................................................................................................................................................8-15

IQ Fractional Representation.............................................................................................................8-15 Traditional “Q” Math Approach........................................................................................................8-16 IQmath Approach ..............................................................................................................................8-18

IQmath Library ......................................................................................................................................8-23 Converting ADC Results into IQ Format...............................................................................................8-25 AC Induction Motor Example ................................................................................................................8-26 IQmath Summary ...................................................................................................................................8-32 Lab 8: IQmath & Floating-Point FIR Filter..........................................................................................8-33

8 - 2 C2000 Piccolo Workshop - Numerical Concepts

Numbering System Basics

Numbering System Basics Given the ability to perform arithmetic processes (addition and multiplication) with the C28x, it is important to understand the underlying mathematical issues which come into play. Therefore, we shall examine the numerical concepts which apply to the C28x and, to a large degree, most processors.

Binary Numbers The binary numbering system is the simplest numbering scheme used in computers, and is the basis for other schemes. Some details about this system are:

• It uses only two values: 1 and 0 • Each binary digit, commonly referred to as a bit, is one “place” in a binary number

and represents an increasing power of 2. • The least significant bit (LSB) is to the right and has the value of 1. • Values are represented by setting the appropriate 1's in the binary number. • The number of bits used determines how large a number may be represented.

Examples: 01102 = (0 * 8) + (1 * 4) + (1 * 2) + (0 * 1) = 610111102 = (1 * 16) + (1 * 8) + (1 * 4) + (1 * 2) + (0 * 1) = 3010

Two's Complement Numbers Notice that binary numbers can only represent positive numbers. Often it is desirable to be able to represent both positive and negative numbers. The two's complement numbering system modifies the binary system to include negative numbers by making the most significant bit (MSB) negative. Thus, two's complement numbers:

• Follow the binary progression of simple binary except that the MSB is negative — in addition to its magnitude

• Can have any number of bits — more bits allow larger numbers to be represented

Examples: 0110 = (0 * -8) + (1 * 4) + (1 * 2) + (0 * 1) = 62 10

111102 = (1 * -16) + (1 * 8) + (1 * 4) + (1 * 2) + (0 * 1) = -210

The same binary values are used in these examples for two's complement as were used above for binary. Notice that the decimal value is the same when the MSB is 0, but the decimal value is quite different when the MSB is 1.

Two operations are useful in working with two's complement numbers: • The ability to obtain an additive inverse of a value • The ability to load small numbers into larger registers (by sign extending)



To load small two's complement numbers into larger registers: The MSB of the original number must carry to the MSB of the number when represented in the larger register.

1. Load the small number “right justified” into the larger register.

2. Copy the sign bit (the MSB) of the original number to all unfilled bits to the left in the register (sign extension).

Consider our two previous values, copied into an 8-bit register:

Examples: Original No. 0 1 1 02 = 610 1 1 1 1 02 = -210

1. Load low 0 1 1 0 1 1 1 1 0

2. Sign Extend 0 0 0 0 0 1 1 0 = 4 + 2 = 6 1 1 1 1 1 1 1 0 = -128 + 64 + ... + 2 = -2

Integer Basics

Integer Basics

Unsigned Binary Integers0100b = (0*23)+(1*22)+(0*22)+(0*20) = 41101b = (1*23)+(1*22)+(0*21)+(1*20) = 13

Signed Binary Integers (2’s Complement)0100b = (0*-23)+(1*22)+(0*22)+(0*20) = 41101b = (1*-23)+(1*22)+(0*21)+(1*20) = -3

2323±2n-1±2n-1 2222 2121 2020



Sign Extension Mode The C28x can operate on either unsigned binary or two's complement operands. The “Sign Extension Mode” (SXM) bit, present within a status register of the C28x, identifies whether or not the sign extension process is used when a value is brought into the accumulator. It is good programming practice to always select the desired SXM at the beginning of a module to assure the proper mode.

What is Sign Extension?When moving a value from a narrowed width location to a wider width location, the sign bit is extended to fill the width of the destinationSign extension applies to signed numbers onlyIt keeps negative numbers negative!Sign extension controlled by SXM bit in ST0 register; When SXM = 1, sign extension happens automatically

4 bit Example: Load a memory value into the ACC

1101memory = -23 + 22 + 20 = -3

ACC = -27 + 26 + 25 + 24 + 23 + 22 + 20

= -128 + 64 + 32 + 16 + 8 + 4 + 1= -3

Load and sign extend

1111 1101


Binary Multiplication

Binary Multiplication Now that you understand two's complement numbers, consider the process of multiplying two two's complement values. As with “long hand” decimal multiplication, we can perform binary multiplication one “place” at a time, and sum the results together at the end to obtain the total product.

Note: This is not the method the C28x uses in multiplying numbers — it is merely a way of observing how binary numbers work in arithmetic processes.

The C28x uses 16-bit operands and a 32-bit accumulator. For the sake of clarity, consider the example below where we shall investigate the use of 4-bit values and an 8-bit accumulation:

Integer Multiplication (signed)

0100x 1101

000001000000000 000100 11100 11110100

Accumulator

Data Memory

1111010011110100

4 x -3

4 x -3

-12-12

?

In this example, consider the following: • What are the two input values, and the expected result? • Why are the “partial products” shifted left as the calculation continues? • Why is the final partial product “different” than the others? • What is the result obtained when adding the partial products? • How shall this result be loaded into the accumulator? • How shall we fill the remaining bit? Is this value still the expected one? • How can the result be stored back to memory? What problems arise?


Binary Multiplication

Note: With two’s complement multiplication, the leading “1” in the second multiplicand is a sign bit. If the sign bit is “1”, then take the 2’s complement of the first multiplicand. Additionally, each partial product must be sign-extended for correct computation.

Note: All of the above questions except the final one are addressed in this module. The last question may have several answers:

• Store the lower accumulator to memory. What problem is apparent using this

method in this example? • Store the upper accumulator back to memory. Wouldn't this create a loss of

precision, and a problem in how to interpret the results later? • Store both the upper and lower accumulator to memory. This solves the above

problems, but creates some new ones: − Extra code space, memory space, and cycle time are used − How can the result be used as the input to a subsequent calculation? Is such a

condition likely (consider any “feedback” system)?

From this analysis, it is clear that integers do not behave well when multiplied. Might some other type of number system behave better? Is there a number system where the results of a multiplication are bounded?


Binary Fractions

Binary Fractions Given the problems associated with integers and multiplication, consider the possibilities of using fractional values. Fractions do not grow when multiplied, therefore, they remain representable within a given word size and solve the problem. Given the benefit of fractional multiplication, consider the issues involved with using fractions:

• How are fractions represented in two's complement? • What issues are involved when multiplying two fractions?

Representing Fractions in Binary In order to represent both positive and negative values, the two's complement process will again be used. However, in the case of fractions, we will not set the LSB to 1 (as was the case for integers). When one considers that the range of fractions is from -1 to ~+1, and that the only bit which conveys negative information is the MSB, it seems that the MSB must be the “negative ones position.” Since binary representation is based on powers of two, it follows that the next bit would be the “one-halves” position, and that each following bit would have half the magnitude again. Considering, as before, a 4-bit model, we have the representation shown in the following example.

1 . 0 1 1 = -1 + 1/4 + 1/8 = -5/8

-1 1/2 1/4 1/8

Fraction Basics

Fraction Basics

-20-20 2-12-1 2-22-2 2-32-3

•1101b = (1*-20)+(1*2-1)+(0*2-2)+(1*2-3)

= -1 + 1/2 + 1/8= -3/8

Fractions have the nice property thatfraction x fraction = fraction

2-(n-1)2-(n-1)


Binary Fractions

Multiplying Binary Fractions When the C28x performs multiplication, the process is identical for all operands, integers or fractions. Therefore, the user must determine how to interpret the results. As before, consider the 4-bit multiply example:

Fraction Multiplication

0100x 1101

000001000000000 000100 11100 11110100

1111010011110100

1/2x -3/8

-3/16

Accumulator

.

.

Data Memory -1/41110.

As before, consider the following: • What are the two input values and the expected result? • As before, “partial products” are shifted left and the final is negative. • How is the result (obtained when adding the partial products) read? • How shall this result be loaded into the accumulator? • How shall we fill the remaining bit? Is this value still the expected one? • How can the result be stored back to memory? What problems arise?

To “read” the results of the fractional multiply, it is necessary to locate the binary point (the base 2 equivalent of the base 10 decimal point). Start by identifying the location of the binary point in the input values. The MSB is an integer and the next bit is 1/2, therefore, the binary point would be located between them. In our example, therefore, we would have three bits to the right of the binary point in each input value. For ease of description, we can refer to these as “Q3” numbers, where Q refers to the number of places to the right of the point.

When multiplying numbers, the Q values add. Thus, we would (mentally) place a binary point above the sixth LSB. We can now calculate the “Q6” result more readily.


Binary Fractions

As with integers, the results are loaded low and the MSB is a sign extension of the seventh bit. If this value were loaded into the accumulator, we could store the results back to memory in a variety of ways:

• Store both low and high accumulator values back to memory. This offers maximum detail, but has the same problems as with integer multiply.

• Store only the high (or low) accumulator back to memory. This creates a potential for a memory littered with varying Q-types.

• Store the upper accumulator shifted to the left by 1. This would store values back to memory in the same Q format as the input values, and with equal precision to the inputs. How shall the left shift be performed? Here’s three methods: − Explicit shift (C or assembly code) − Shift on store (assembly code) − Use Product Mode shifter (assembly code)


Fraction Coding

Fraction Coding Although COFF tools recognize values in integer, hex, binary, and other forms, they understand only integer, or non-fractional values. To use fractions within the C28x, it is necessary to describe them as though they were integers. This turns out to be a very simple trick. Consider the following number lines:

Coding Traditional 16-bit Q15 Fractions

Fraction

⇒∗ 32768

(215)

C-code example: y = 0.707 * xvoid main(void){

int16 coef = 32768*707/1000; // 0.707 in Q15int16 x, y;y = (int16)( (int32)coef * (int32)x ) >> 15);

}

~1

½

0

-½

-1

0x7FFF

0x4000

0x0000

0xC000

0x8000

32767

16384

0

-16384

-32768Integer

By multiplying a fraction by 32K (32768), a normalized fraction is created, which can be passed through the COFF tools as an integer. Once in the C28x, the normalized fraction looks and behaves exactly as a fraction. Thus, when using fractional constants in a C28x program, the coder first multiplies the fraction by 32768, and uses the resulting integer (rounded to the nearest whole value) to represent the fraction.

The following is a simple, but effective method for getting fractions past the assembler:

1. Express the fraction as a decimal number (drop the decimal point).

2. Multiply by 32768.

3. Divide by the proper multiple of 10 to restore the decimal position.

Examples: • To represent 0.62: 32768 x 62 / 100 • To represent 0.1405: 32768 x 1405 / 10000

This method produces a valid number accurate to 16 bits. You will not need to do the math yourself, and changing values in your code becomes rather simple.


Fractional vs. Integer Representation

Fractional vs. Integer Representation Integer vs. Fractions

Range Precision

Integer determined 1by # of bits

Fraction ~+1 to -1 determinedby # of bits

Integers grow when you multiply themFractions have limited range

Fractions can still grow when you add themScaling an application is time consuming

Are there any other alternatives?

The C28x accumulator, a 32-bit register, adds extra range to integer calculations, but this becomes a problem in storing the results back to 16-bit memory.

Conversely, when using fractions, the extra accumulator bits increase precision, which helps minimize accumulative errors. Since any number is accurate (at best) to ± one-half of a LSB, summing two of these values together would yield a worst case result of 1 LSB error. Four summations produce two LSBs of error. By 256 summations, eight LSBs are “noisy.” Since the accumulator holds 32 bits of information, and fractional results are stored from the high accumulator, the extra range of the accumulator is a major benefit in noise reduction for long sum-of-products type calculations.


Floating-Point

Floating-Point IEEE-754 Single Precision Floating-Point

Example: 0x41200000 = 0 100 0001 0 010 0000 0000 ... 0000 bs e = 130 f = 2-2 = 0.25

⇒ Case 3 v = (-10)*2(130-127)*1.25 = 10.0

s eeeeeeee fffffffffffffffffffffff031 30 23 22

23 bit mantissa (fraction)8 bit exponent1 bit sign

Case 1: if e = 255 and f ≠ 0, then v = NaNCase 2: if e = 255 and f = 0, then v = [(-1)s]*infinityCase 3: if 0 < e < 255, then v = [(-1)s]*[2(e-127)]*(1.f)Case 4: if e = 0 and f ≠ 0, then v = [(-1)s]*[2(-126)]*(0.f)Case 5: if e = 0 and f = 0, then v = [(-1)s]*0

Advantage ⇒ Exponent gives large dynamic rangeDisadvantage ⇒ Precision of a number depends on its exponent

Normalizedvalues

Number Line Insight

Floating-Point:

0+∞ -∞0+∞ -∞

Non-uniform distributionPrecision greatest near zeroLess precision the further you get from zero


Floating-Point

Floating-Point Pros and Cons

AdvantagesEasy to write codeNo scaling required

DisadvantagesSomewhat higher device costMay offer insufficient precision for some calculations due to 23 bit mantissa and the influence of the exponent

What if you don’t have the luxury of using a floating-point C28x device?


IQmath

IQmath Implementing complex digital control algorithms on a Digital Signal Processor (DSP), or any other DSP capable processor, typically come across the following issues: • Algorithms are typically developed using floating-point math • Floating-point devices are more expensive than fixed-point devices • Converting floating-point algorithms to a fixed-point device is very time consuming • Conversion process is one way and therefore backward simulation is not always possible

The design may initially start with a simulation (i.e. MatLab) of a control algorithm, which typically would be written in floating-point math (C or C++). This algorithm can be easily ported to a floating-point device, however because of cost reasons most likely a 16-bit or 32-bit fixed-point device would be used in many target systems.

The effort and skill involved in converting a floating-point algorithm to function using a 16-bit or 32-bit fixed-point device is quite significant. A great deal of time (many days or weeks) would be needed for reformatting, scaling and coding the problem. Additionally, the final implementation typically has little resemblance to the original algorithm. Debugging is not an easy task and the code is not easy to maintain or document.

IQ Fractional Representation A new approach to fixed-point algorithm development, termed “IQmath”, can greatly simplify the design development task. This approach can also be termed “virtual floating-point” since it looks like floating-point, but it is implemented using fixed-point techniques.

IQ Fractional Representation

S IIIIIIII fffffffffffffffffffffff031

32 bit mantissa

Advantage ⇒ Precision same for all numbers in an IQ formatDisadvantage ⇒ Limited dynamic range compared to floating-point

-2I + 2I-1 + … + 21 + 20 . 2-1 + 2-2 + … + 2-Q

I8Q24 Example: 0x41200000= 0100 0001 . 0010 0000 0000 0000 0000 0000 b = 26 + 20 + 2-3 = 65.125


IQmath

The IQmath approach enables the seamless portability of code between fixed and floating-point devices. This approach is applicable to many problems that do not require a large dynamic range, such as motor or digital control applications.

IQ Fractions: uniform distribution (same precision everywhere)

0+∞ -∞

Number Line InsightDistributions

Floating-Point: non-uniform distribution (variable precision)

0+∞ -∞

Both floating-point and IQ formats have 232

possible values on the number lineIt’s how each distributes these values that differs

Traditional “Q” Math Approach

Traditional 32-bit “Q” Math Approachy = mx + b

Y = ((int64) M * (int64) X + (int64) B << Q) >> Q;in C:

Note: Requires support for 64-bit integer data type in compiler

<< 24Align DecimalPoint for Add

I8 Q24 M

X

B

Y

I8 Q24

I8 Q24

I16 Q48

ssssssssssssssssssI8 Q24

ssssI8 Q48

I16 Q48

sssssssssssssssssI16 Q24 I8 Q24

>> 24Align DecimalPoint for Store


IQmath

The traditional approach to performing math operations, using fixed-point numerical techniques can be demonstrated using a simple linear equation example. The floating-point code for a linear equation would be:

float Y, M, X, B; Y = M * X + B;

For the fixed-point implementation, assume all data is 32-bits, and that the "Q" value, or location of the binary point, is set to 24 fractional bits (Q24). The numerical range and resolution for a 32-bit Q24 number is as follows: Q value Min Value Max Value Resolution

Q24 -2(32-24) = -128.000 000 00 2(32-24) – (½)24 = 127.999 999 94 (½)24 = 0.000 000 06 The C code implementation of the linear equation is:

int32 Y, M, X, B; // numbers are all Q24 Y = ((int64) M * (int64) X + (int64) B << 24) >> 24;

Compared to the floating-point representation, it looks quite cumbersome and has little resem-blance to the floating-point equation. It is obvious why programmers prefer using floating-point math. The slide shows the implementation of the equation on a processor containing hardware that can perform a 32x32 bit multiplication, 64-bit addition and 64-bit shifts (logical and arithmetic) effi-ciently. The basic approach in traditional fixed-point "Q" math is to align the binary point of the operands that get added to or subtracted from the multiplication result. As shown in the slide, the multipli-cation of M and X (two Q24 numbers) results in a Q48 value that is stored in a 64-bit register. The value B (Q24) needs to be scaled to a Q48 number before addition to the M*X value (low order bits zero filled, high order bits sign extended). The final result is then scaled back to a Q24 number (arithmetic shift right) before storing into Y (Q24). Many programmers may be familiar with 16-bit fixed-point "Q" math that is in common use. The same example using 16-bit numbers with 15 fractional bits (Q15) would be coded as follows:

int16 Y, M, X, B; // numbers are all Q15 Y = ((int32) M * (int32) X + (int32) B << 15) >> 15;

In both cases, the principal methodology is the same. The binary point of the operands that get added to or subtracted from the multiplication result must be aligned.


IQmath

IQmath Approach

32-bit IQmath Approachy = mx + b

I8 Q24I16 Q48

M

X

B

Y

>> 24Align DecimalPoint Of Multiply

I8 Q24

I8 Q24

sssssssssssssssssI16 Q24

I8 Q24I8 Q24

Y = ((int64) M * (int64) X) >> Q + B;in C:

In the "IQmath" approach, rather then scaling the operands, which get added to or subtracted from the multiplication result, we do the reverse. The multiplication result binary point is scaled back such that it aligns to the operands, which are added to or subtracted from it. The C code implementation of this is given by linear equation below:

int32 Y, M, X, B; Y = ((int64) M * (int64) X) >> 24 + B;

The slide shows the implementation of the equation on a processor containing hardware that can perform a 32x32 bit multiply, 32-bit addition/subtraction and 64-bit logical and arithmetic shifts efficiently. The key advantage of this approach is shown by what can then be done with the C and C++ com-piler to simplify the coding of the linear equation example. Let’s take an additional step and create a multiply function in C that performs the following op-eration:

int32 _IQ24mpy(int32 M, int32 X) { return ((int64) M * (int64) X) >> 24; } The linear equation can then be written as follows:

Y = _IQ24mpy(M , X) + B;

Already we can see a marked improvement in the readability of the linear equation.


IQmath

Using the operator overloading features of C++, we can overload the multiplication operand "*" such that when a particular data type is encountered, it will automatically implement the scaled multiply operation. Let’s define a data type called "iq" and assign the linear variables to this data type:

iq Y, M, X, B // numbers are all Q24 The overloading of the multiply operand in C++ can be defined as follows:

iq operator*(const iq &M, const iq &X){return((int64)M*(int64) X) >> 24;} Then the linear equation, in C++, becomes:

Y = M * X + B; This final equation looks identical to the floating-point representation. It looks "natural". The four approaches are summarized in the table below:

Math Implementations Linear Equation Code 32-bit floating-point math in C Y = M * X + B;

32-bit fixed-point "Q" math in C Y = ((int64) M * (int64) X) + (int64) B << 24) >> 24; 32-bit IQmath in C Y = _IQ24mpy(M, X) + B;

32-bit IQmath in C++ Y = M * X + B; Essentially, the mathematical approach of scaling the multiplier operand enables a cleaner and a more "natural" approach to coding fixed-point problems. For want of a better term, we call this approach "IQmath" or can also be described as "virtual floating-point".


IQmath

IQmath ApproachMultiply Operation

Y = ((i64) M * (i64) X) >> Q + B;

_IQmpy(M,X) == ((i64) M * (i64) X) >> Q

Redefine the multiply operation as follows:

Y = _IQmpy(M,X) + B;

This simplifies the equation as follows:

MOVL XT,@MIMPYL P,XT,@X ; P = low 32-bits of M*X QMPYL ACC,XT,@X ; ACC = high 32-bits of M*XLSL64 ACC:P,#(32-Q) ; ACC = ACC:P << 32-Q

; (same as P = ACC:P >> Q)ADDL ACC,@B ; Add BMOVL @Y,ACC ; Result = Y = _IQmpy(M*X) + B; 7 Cycles

C28x compiler supports “_IQmpy” intrinsic; assembly code generated:

IQmath ApproachIt looks like floating-point!

float Y, M, X, B;

Y = M * X + B;

Floating-Point

long Y, M, X, B;

Y = ((i64) M * (i64) X + (i64) B << Q)) >> Q;

TraditionalFix-Point Q

_iq Y, M, X, B;

Y = _IQmpy(M, X) + B;

“IQmath”In C

iq Y, M, X, B;

Y = M * X + B;

“IQmath”In C++

“IQmath” code is easy to read!


IQmath

IQmath ApproachGLOBAL_Q simplification

#define GLOBAL_Q 18 // set in “IQmathLib.h” file

_iq Y, M, X, B;

Y = _IQmpy(M,X) + B; // all values are in Q = 18

GLOBAL_Q

User selects “Global Q” value for the whole application

based on the required dynamic range or resolution, for example:

The user can also explicitly specify the Q value to use:_iq20 Y, M, X, B;

Y = _IQ20mpy(M,X) + B; // all values are in Q = 20

0.000 000 06-128.000 000 00127.999 999 94240.000 001-2048.000 0002047.999 99920

0.000 000 004-8.000 000 0007.999 999 99628ResolutionMin ValMax ValGLOBAL_Q

The basic "IQmath" approach was adopted in the creation of a standard math library for the Texas Instruments TMS320C28x DSP fixed-point processor. This processor contains efficient hardware for performing 32x32 bit multiply, 64-bit shifts (logical and arithmetic) and 32-bit add/subtract operations, which are ideally suited for 32 bit "IQmath". Some enhancements were made to the basic "IQmath" approach to improve flexibility. They are: Setting of GLOBAL_Q Parameter Value: Depending on the application, the amount of numerical resolution or dynamic range required may vary. In the linear equation example, we used a Q value of 24 (Q24). There is no reason why any value of Q can't be used. In the "IQmath" library, the user can set a GLOBAL_Q parameter, with a range of 1 to 30 (Q1 to Q30). All functions used in the program will use this GLOBAL_Q value. For example:

#define GLOBAL_Q 18 Y = _IQmpy(M, X) + B; // all values use GLOBAL_Q = 18

If, for some reason a particular function or equation requires a different resolution, then the user has the option to implicitly specify the Q value for the operation. For example:

Y = _IQ23mpy(M,X) + B; // all values use Q23, including B and Y The Q value must be consistent for all expressions in the same line of code.


IQmath

IQmath Provides Compatibility Between Floating-Point and Fixed-Point

All “IQmath” operations have an equivalent floating-point operation

Compile & Runon Fixed-Point

F282xx

Y = _IQmpy(M, X) + B;

#if MATH_TYPE == IQ_MATH #if MATH_TYPE == FLOAT_MATH

Y = (float)M * (float)X + (float)B;

1) Develop any mathematical function

2) Select math type in IQmathLib.h

3) Compiler automatically converts to:

Floating-Point Math Code

Fixed-Point Math Code

Compile & Runon Floating-Point

F283xx *

* Can also compile floating-point code on any floating-point compiler (e.g., PC, Matlab, fixed-point w/ RTS lib, etc.)

Selecting FLOAT_MATH or IQ_MATH Mode: As was highlighted in the introduction, we would ideally like to be able to have a single source code that can execute on a floating-point or fixed-point target device simply by recompiling the code. The "IQmath" library supports this by setting a mode, which selects either IQ_MATH or FLOAT_MATH. This operation is performed by simply redefining the function in a header file. For example:

#if MATH_TYPE == IQ_MATH #define _IQmpy(M , X) _IQmpy(M , X) #elseif MATH_TYPE == FLOAT_MATH #define _IQmpy(M , X) (float) M * (float) X #endif

Essentially, the programmer writes the code using the "IQmath" library functions and the code can be compiled for floating-point or "IQmath" operations.


IQmath Library

IQmath Library IQmath Library: Math & Trig Functions

Accuracy of functions/operations approx ~28 to ~31 bits

IQsin(A),IQcos(A)IQsinPU(A),IQcosPU(A)

IQasin(A),IQacos(A)IQatan(A),IQatan2(A,B)

IQatan2PU(A,B)IQsqrt(A),IQisqrt(A)

IQmag(A,B)IQexp(A)

_IQsin(A), _IQcos(A)_IQsinPU(A), _IQcosPU(A)

_IQasin(A),_IQacos(A)_IQatan(A), _IQatan2(A,B)

_IQatan2PU(A,B)_IQsqrt(A), _IQisqrt(A)

_IQmag(A,B)_IQexp(A)

sin(A),cos(A) sin(A*2pi),cos(A*2pi)

asin(A),acos(A)atan(A),atan2(A,B)

atan2(A,B)/2pisqrt(A),1/sqrt(A)sqrt(A*A + B*B)

exp(A)

trigand

powerfunctions

IQsat(A,Pos,Neg)_IQsat(A,Pos,Neg)if(A > Pos) A = Posif(A < Neg) A = Neg

saturation

A – BA - BA - Bsubstract>, >=, <, <=, ==, |=, &&, || >, >=, <, <=, ==, |=, &&, ||>, >=, <, <=, ==, |=, &&, ||boolean

A + BA + BA + BaddA / B_IQdiv (A , B)A / B divideA * B_IQmpy(A , B)A * Bmultiply

A = IQ(1.2345)A = _IQ(1.2345)A = 1.2345constantiq A, B;_iq A, B;float A, B;type

“IQmath” in C++“IQmath” in CFloating-PointOperation

Additionally, the "IQmath" library contains DSP library modules for filters (FIR & IIR) and Fast Fourier Transforms (FFT & IFFT).

IQmath Library: Conversion Functions

IQmath.lib > contains library of math functions IQmathLib.h > C header fileIQmathCPP.h > C++ header file

atoIQ(char)_atoIQ(char)atof(char)string to iqIQtoQN(A)_IQtoQN(A)Aiq to qNQNtoIQ(A)_QNtoIQ(A)AqN to iq

IQmpyI32int(A,B)_IQmpyI32int(A,B)(long) (A * (float) B)integer(iq*long)IQmpyI32frac(A,B)_IQmpyI32frac(A,B)A - (long) (A * (float) B)fraction(iq*long)

IQtoF(A)_IQtoF(A)AIQ to float

IQmpyI32(A,B)_IQmpyI32(A,B)A * (float) Biq = iq*longIQfrac(A)_IQfrac(A)A – (long) Afraction(iq)IQint(A)_IQint(A)(long) Ainteger(iq)

IQNtoIQ(A)_IQNtoIQ(A)AiqN to iqIQtoIQN(A)_IQtoIQN(A)Aiq to iqN

“IQmath” in C++“IQmath” in CFloating-PointOperation

IQtoA(A,B,C)_IQtoA(A,B,C)sprintf(A,B,C)IQ to ASCII


IQmath Library

16 vs. 32 Bits The "IQmath" approach could also be used on 16-bit numbers and for many problems, this is suf-ficient resolution. However, in many control cases, the user needs to use many different "Q" val-ues to accommodate the limited resolution of a 16-bit number. With DSP devices like the TMS320C28x processor, which can perform 16-bit and 32-bit math with equal efficiency, the choice becomes more of productivity (time to market). Why bother spending a whole lot of time trying to code using 16-bit numbers when you can simply use 32-bit numbers, pick one value of "Q" that will accommodate all cases and not worry about spending too much time optimizing. Of course there is a concern on data RAM usage if numbers that could be represented in 16 bits all use 32 bits. This is becoming less of an issue in today's processors because of the finer tech-nology used and the amount of RAM that can be cheaply integrated. However, in many cases, this problem can be mitigated by performing intermediate calculations using 32-bit numbers and converting the input from 16 to 32 bits and converting the output back to 16 bits before storing the final results. In many problems, it is the intermediate calculations that require additional ac-curacy to avoid quantization problems.


Converting ADC Results into IQ Format

Converting ADC Results into IQ Format

_iq Result;

void main(void)

{

// Convert the ADC result into global IQ format valued between 0.0 and 1.0

Result = _IQ12toIQ( (_iq)AdcResult.ADCRESULT0 );

}

Getting the ADC Result into IQ FormatAdcResult.

ADCRESULTx

32-bit long15 031

Do not sign extend

Notice that the 32-bit long is already in IQ12 format

// Optional: scale by ADC full-scale range to get 0.0 to 3.3

// (if you prefer to think/scale in terms of voltage)

Result = _IQmpy( _iq(3.3), Result);

}

x x x xx x x xx x x x0 0 0 00 0 0 0 0 0 0 00 0 0 0 0 0 0 0

x x x xx x x xx x x x0 0 0 0

As you may recall, the converted values of the ADC are placed in the lower 12 bits of the ADCRESULT0 register. Before these values are filtered using the IQmath library, they need to to be put into the IQ format as a 32-bit long. For uni-polar ADC inputs (i.e., 0 to 3.3 V inputs), a conversion to global IQ format can be achieved with:

IQresult_unipolar = _IQmpy(_IQ(3.3),_IQ12toIQ((_iq) AdcResult.ADCRESULT0)); How can we modify the above to recover bi-polar inputs, for example +-1.65 volts? One could do the following to offset the +1.65V analog biasing applied to the ADC input:

IQresult_bipolar = _IQmpy(_IQ(3.3),_IQ12toIQ((_iq) AdcResult.ADCRESULT0)) - _IQ(1.65); However, one can see that the largest intermediate value the equation above could reach is 3.3. This means that it cannot be used with an IQ data type of IQ30 (IQ30 range is -2 < x < ~2). Since the IQmath library supports IQ types from IQ1 to IQ30, this could be an issue in some applica-tions. The following clever approach supports IQ types from IQ1 to IQ30:

IQresult_bipolar = _IQmpy(_IQ(1.65),_IQ15toIQ((_iq) ((int16) (AdcResult.ADCRESULT0 ^ 0x8000))));

The largest intermediate value that this equation could reach is 1.65. Therefore, IQ30 is easily supported.


AC Induction Motor Example

AC Induction Motor Example AC Induction Motor Example

One of the more complex motor control algorithms

Sensorless, ACI induction machine direct rotor flux controlGoal: motor speed estimation & alpha-axis stator current estimation

The "IQmath" approach is ideally suited for applications where a large numerical dynamic range is not required. Motor control is an example of such an application (audio and communication algorithms are other applications). As an example, the IQmath approach has been applied to the sensor-less direct field control of an AC induction motor. This is probably one of the most chal-lenging motor control problems and as will be shown later, requires numerical accuracy greater then 16-bits in the control calculations. The above slide is a block diagram representation of the key control blocks and their interconnec-tions. Essentially this system implements a "Forward Control" block for controlling the d-q axis motor current using PID controllers and a "Feedback Control" block using back emf's integration with compensated voltage from current model for estimating rotor flux based on current and volt-age measurements. The motor speed is simply estimated from rotor flux differentiation and open-loop slip computation. The system was initially implemented on a "Simulator Test Bench" which uses a simulation of an "AC Induction Motor Model" in place of a real motor. Once working, the system was then tested using a real motor on an appropriate hardware platform. Each individual block shown in the slide exists as a stand-alone C/C++ module, which can be interconnected to form the complete control system. This modular approach allows reusability and portability of the code. The next few slides show the coding of one particular block, PARK Transform, using floating-point and "IQmath" approaches in C:



AC Induction Motor ExamplePark Transform – floating-point C code

#include “math.h”

#define TWO_PI 6.28318530717959

void park_calc(PARK *v)

{

float cos_ang , sin_ang;

sin_ang = sin(TWO_PI * v->ang);

cos_ang = cos(TWO_PI * v->ang);

v->de = (v->ds * cos_ang) + (v->qs * sin_ang);

v->qe = (v->qs * cos_ang) - (v->ds * sin_ang);

}

AC Induction Motor ExamplePark Transform - converting to “IQmath” C code

#include “math.h”

#define TWO_PI 6.28318530717959

void park_calc(PARK *v)

{

float cos_ang , sin_ang;

sin_ang = sin(TWO_PI * v->ang);

cos_ang = cos(TWO_PI * v->ang);

v->de = (v->ds * cos_ang) + (v->qs * sin_ang);

v->qe = (v->qs * cos_ang) - (v->ds * sin_ang);

}

#include “IQmathLib.h”

_IQ(6.28318530717959)

_iq

_IQsin(_IQmpy(TWO_PI , v->ang));

_IQcos(_IQmpy(TWO_PI , v->ang));

_IQmpy(v->ds , cos_ang) + _IQmpy(v->qs , sin_ang);

_IQmpy(v->qs , cos_ang) - _IQmpy(v->ds , sin_ang);

The complete system was coded using "IQmath". Based on analysis of coefficients in the system, the largest coefficient had a value of 33.3333. This indicated that a minimum dynamic range of 7 bits (+/-64 range) was required. Therefore, this translated to a GLOBAL_Q value of 32-7 = 25 (Q25). Just to be safe, the initial simulation runs were conducted with GLOBAL_Q = 24 (Q24)



value. The plots start from a step change in reference speed from 0.0 to 0.5 and 1024 samples are taken.

AC Induction Motor ExampleGLOBAL_Q = 24, system stable

IQmath: speed IQmath: current

Floating-Point: speed Floating-Point: current

The speed eventually settles to the desired reference value and the stator current exhibits a clean and stable oscillation. The block diagram slide shows at which points in the control system the plots are taken from.

I8Q24 Fractions:

0+∞ -∞

What’s Happening Here?Equal Precision in the Computation Region

In the region where these particular computations occur, the precision of single-precision floating-point just happens to equal the precision of the I8Q24 format.

So, both produce similar results!

Floating-Point:

0+∞ -∞

Same precision as I8Q24



AC Induction Motor ExampleGLOBAL_Q = 27, system unstable

IQmath: speed

IQmath: current

AC Induction Motor ExampleGLOBAL_Q = 16, system unstable

IQmath: speed

IQmath: current



With the ability to select the GLOBAL_Q value for all calculations in the "IQmath", an experi-ment was conducted to see what maximum and minimum Q value the system could tolerate be-fore it became unstable. The results are tabulated in the slide below:

AC Induction Motor ExampleQ stability range

The developer must pick the right GLOBAL_Q value!

Unstable(not enough resolution, quantization problems)Q18 to Q0

StableQ26 to Q19

Unstable(not enough dynamic range)Q31 to Q27

Stability RangeQ range

The above indicates that, the AC induction motor system that we simulated requires a minimum of 7 bits of dynamic range (+/-64) and requires a minimum of 19 bits of numerical resolution (+/-0.000002). This confirms our initial analysis that the largest coefficient value being 33.33333 required a minimum dynamic range of 7 bits. As a general guideline, users using IQmath should examine the largest coefficient used in the equations and this would be a good starting point for setting the initial GLOBAL_Q value. Then, through simulation or experimentation, the user can reduce the GLOBAL_Q until the system resolution starts to cause instability or performance deg-radation. The user then has a maximum and minimum limit and a safe approach is to pick a mid-point. What the above analysis also confirms is that this particular problem does require some calcula-tions to be performed using greater then 16 bit precision. The above example requires a mini-mum of 7 + 19 = 26 bits of numerical accuracy for some parts of the calculations. Hence, if one was implementing the AC induction motor control algorithm using a 16 bit fixed-point DSP, it would require the implementation of higher precision math for certain portions. This would take more cycles and programming effort. The great benefit of using GLOBAL_Q is that the user does not necessarily need to go into de-tails to assign an individual Q for each variable in a whole system, as is typically done in conven-tional fixed-point programming. This is time consuming work. By using 32-bit resolution and the "IQmath" approach, the user can easily evaluate the overall resolution and quickly implement a typical digital motor control application without quantization problems.



AC Induction Motor ExamplePerformance comparisons

Benchmark C28x C C28x C C28x Cfloating-point floating-point IQmathstd. RTS lib fast RTS lib v1.4d(150 MHz) (150 MHz) (150 MHz)

B1: ACI module cycles 401 401 625B2: Feedforward control cycles 421 371 403B3: Feedback control cycles 2336 792 1011Total control cycles (B2+B3) 2757 1163 1414% of available MHz used 36.8% 15.5% 18.9%(20 kHz control loop)

Notes: C28x compiled on codegen tools v5.0.0, -g (debug enabled), -o3 (max. optimization)fast RTS lib v1.0beta1IQmath lib v1.4d

Using the profiling capabilities of the respective DSP tools, the table above summarizes the num-ber of cycles and code size of the forward and feedback control blocks. The MIPS used is based on a system sampling frequency of 20 kHz, which is typical of such sys-tems.


IQmath Summary

IQmath Summary IQmath Approach Summary

Seamless portability of code between fixed and floating-point devices

User selects target math type in “IQmathLib.h” file#if MATH_TYPE == IQ_MATH#if MATH_TYPE == FLOAT_MATH

One source code set for simulation vs. target deviceNumerical resolution adjustability based on application requirement

Set in “IQmathLib.h” file#define GLOBAL_Q 18

Explicitly specify Q value_iq20 X, Y, Z;

Numerical accuracy without sacrificing time and cyclesRapid conversion/porting and implementation of algorithms

IQmath library is freeware - available from TI DSP websitehttp://www.ti.com/c2000

“IQmath” + fixed-point processor with 32-bit capabilities =

The IQmath approach, matched to a fixed-point processor with 32x32 bit capabilities enables the following:

• Seamless portability of code between fixed and floating-point devices • Maintenance and support of one source code set from simulation to target device • Adjustability of numerical resolution (Q value) based on application requirement • Implementation of systems that may otherwise require floating-point device • Rapid conversion/porting and implementation of algorithms


Lab 8: IQmath & Floating-Point FIR Filter

Lab 8: IQmath & Floating-Point FIR Filter Objective

The objective of this lab is to become familiar with IQmath programming. In the previous lab, ePWM1A was setup to generate a 2 kHz, 25% duty cycle symmetric PWM waveform. The waveform was then sampled with the on-chip analog-to-digital converter. In this lab the sampled waveform will be passed through an FIR filter and displayed using the graphing feature of Code Composer Studio. The filter math type is selected in the “IQmathLib.h” file.

Lab 8: IQmath FIR Filter


ADCRESULT0

ePWM2

connectorwire

ADCINA0

...

datamemory

poin

ter

rew

ind

Display using CCS

TB CounterCompare

Action Qualifier

ePWM1

ePWM2 triggering ADC on period match using SOCA trigger every 20 µs (50 kHz)

FIR Filter

Procedure


on Project Open… and look in C:\C28x\Labs\Lab8. All Build Options have been configured the same as the previous lab. The files used in this lab are: Adc.c Filter.c CodeStartBranch.asm Gpio.c DefaultIsr_8.c Lab_8.cmd DelayUs.asm Main_8.c DSP2803x_GlobalVariableDefs.c PieCtrl_5_6_7_8_9_10.c DSP2803x_Headers_nonBIOS.cmd PieVect_5_6_7_8_9_10.c ECap_7_8_9_10_12.c SysCtrl.c EPwm_7_8_9_10_12.c Watchdog.c



Project Build Options 2. Setup the include search path to include the IQmath header file. Open the Build

Options and select the Compiler tab. In the Preprocessor Category, find the Include Search Path (-i) box and add to the end of the line (preceeded with a semicolon to append this directory to the existing search path):

;..\IQmath\include

3. Setup the library search path to include the IQmath library. Select the Linker tab.

a. In the Libraries Category, find the Search Path (-i) box and enter:

..\IQmath\lib

b. In the Include Libraries (-l) box add to the end of the line (preceeded with a semicolon to append this library to the existing library):

;IQmath.lib

Then select OK to save the Build Options.

Include IQmathLib.h 4. In the CCS project window left click the plus sign (+) to the left of the Include folder.

Edit Lab.h to uncomment the line that includes the IQmathLib.h header file. Next, in the Function Prototypes section, uncomment the function prototype for IQssfir(), the IQ math single-sample FIR filter function. In the Global Variable References section uncomment the two _iq references. Save the changes and close the file.

Inspect Lab_8.cmd 5. Open and inspect Lab_8.cmd. First, notice that a section called “IQmath” is being

linked to L0SARAM. The IQmath section contains the IQmath library functions (code). Second, notice that a section called “IQmathTables” is being linked to the IQTABLES with a TYPE = NOLOAD modifier after its allocation. The IQmath tables are used by the IQmath library functions. The NOLOAD modifier allows the linker to resolve all addresses in the section, but the section is not actually placed into the .out file. This is done because the section is already present in the device ROM (you cannot load data into ROM after the device is manufactured!). The tables were put in the ROM by TI when the device was manufactured. All we need to do is link the section to the addresses where it is known to already reside (the tables are the very first thing in the BOOT ROM, starting at address 0x3FE000). Close the inspected file.



Select a Global IQ value 6. Use File Open… to open c:\C28x\Labs\IQmath\include\IQmathLib.h.

Confirm that the GLOBAL_Q type (near beginning of file) is set to a value of 24. If it is not, modify as necessary:

#define GLOBAL_Q 24

Recall that this Q type will provide 8 integer bits and 24 fractional bits. Dynamic range is therefore -128 < x < +128, which is sufficient for our purposes in the workshop.

Notice that the math type is defined as IQmath by:

#define MATH_TYPE IQ_MATH

Close the file.

IQmath Single-Sample FIR Filter 7. Open and inspect DefaultIsr_8.c. Notice that the ADCINT_ISR calls the IQmath

single-sample FIR filter function, IQssfir(). The filter coefficients have been defined in the beginning of Main_8.c.

8. Open and inspect the IQssfir() function in Filter.c. This is a simple, non-optimized coding of a basic IQmath single-sample FIR filter. Close the inspected files.

Build and Load 9. Click the “Build” button to build and load the project.

Run the Code – Filtered Waveform 10. Open a memory window to view some of the contents of the filtered ADC results buffer.

The address label for the filtered ADC results buffer is AdcBufFiltered. Set the Format to 16-Bit Unsigned Integer. We will be running our code in real-time mode, and will have our window continuously refresh.

Note: For the next step, check to be sure that the jumper wire connecting PWM1A (pin # GPIO-00) to ADCINA0 (pin # ADC-A0) is in place on the Docking Station.

11. Run the code in real-time mode using the GEL function: GEL Realtime Emulation Control Run_Realtime_with_Reset, and watch the memory window update. Verify that the ADC result buffer contains updated values.

12. Open and setup a dual-time graph to plot a 50-point window of the filtered and unfiltered ADC results buffer. Click: View Graph Time/Frequency… and set the following values:



Display Type Dual Time

Start Address – upper display AdcBufFiltered

Start Address – lower display AdcBuf







13. The graphical display should show the generated FIR filtered 2 kHz, 25% duty cycle symmetric PWM waveform in the upper display and the unfiltered waveform generated in the previous lab exercise in the lower display. Notice the shape and phase differences between the waveform plots (the filtered curve has rounded edges, and lags the unfiltered plot by several samples). The amplitudes of both plots should run from 0 to 4095.

14. Open and setup two (2) frequency domain plots – one for the filtered and another for the unfiltered ADC results buffer. Click: View Graph Time/Frequency… and set the following values:

GRAPH #1 GRAPH #2

Display Type FFT Magnitude FFT Magnitude

Start Address AdcBufFiltered AdcBuf

Acquisition Buffer Size 50 50

FFT Framesize 50 50

DSP Data Type 16-bit unsigned integer 16-bit unsigned integer

Sampling Rate (Hz) 50000 50000


15. The graphical displays should show the frequency components of the filtered and unfiltered 2 kHz, 25% duty cycle symmetric PWM waveforms. Notice that the higher frequency components are reduced using the Low-Pass FIR filter in the filtered graph as compared to the unfiltered graph.




End of Exercise



Lab 8 Reference: Low-Pass FIR Filter

Bode Plot of Digital Low Pass Filter

Coefficients: [1/16, 4/16, 6/16, 4/16, 1/16]

Sample Rate: 50 kHz


Control Law Accelerator

Introduction This module explains the operation of the control law accelerator (CLA). The CLA is an independent, fully programmable, 32-bit floating-point math processor that enables concurrent execution into the C28x family. This extends the capabilities of the C28x CPU by adding parallel processing. The CLA has direct access to the ADC result registers, and all ePWM, HRPWM and comparator registers. This allows the CLA to read ADC samples “just-in-time” and significantly reduces the ADC sample to output delay enabling faster system response and higher frequency operation. Utilizing the CLA for time-critical tasks frees up the CPU to perform other system and communication functions concurrently.


Explain the purpose and operation of the Control Law Accelerator (CLA)Describe the CLA initialization procedureReview the CLA registers, instruction set, and programming flow

C2000 Piccolo Workshop - Control Law Accelerator 9 - 1

Module Topics

Module Topics Control Law Accelerator .......................................................................................................................... 9-1

Module Topics......................................................................................................................................... 9-2 Control Law Accelerator (CLA) ............................................................................................................. 9-3

CLA Block Diagram........................................................................................................................... 9-3 CLA Memory and Register Access .................................................................................................... 9-4 CLA Tasks.......................................................................................................................................... 9-4 Control and Execution Registers ........................................................................................................ 9-5 CLA Registers .................................................................................................................................... 9-6 CLA Initialization............................................................................................................................... 9-8 CLA Task Programming .................................................................................................................... 9-9 CLA Instruction Set...........................................................................................................................9-10 CLA Addressing Modes ....................................................................................................................9-11 CLA Code Example...........................................................................................................................9-11 CLA Code Debugging .......................................................................................................................9-12

Lab 9: CLA Floating-Point FIR Filter...................................................................................................9-13

9 - 2 C2000 Piccolo Workshop - Control Law Accelerator

Control Law Accelerator (CLA)

Control Law Accelerator (CLA) Control Law Accelerator (CLA)

CLA is an independent 32-bit floating-point math acceleratorExecutes algorithms independently and in parallel with the main CPUDirect access to ePWM / HRPWM, ADC result and comparator registersResponds to peripheral interrupts independently of CPUFrees-up CPU for other tasks (communications and diagnostics)

C28x CPU

CLAPWM

ADC&

CMP

CLA Block Diagram

CLA Block Diagram

MPERINT1-8

ADCINT1 orEPWM1_INT

ADCINT7 orEPWM7_INT

ADCINT8 orCPU Timer 0

CLA_INT1-8LVF, LUF PIE

C28xCPU

INT11INT12

CLAControl & Execution

Registers

Task Triggers(Peripheral Interrupts)

CLA Program Bus

CLA Data Bus

Prog RAM Data RAM0 Data RAM1MSG RAMsCPU to CLACLA to CPU

Periph. RegsADC Results

ePWMHRPWM

Comparator



CLA Memory and Register Access

CLA Memory and Register Access

Contains CLA program codeMapped to the CPU at resetInitialized by the CPU

CLA Program MemoryUsed to pass data between the CPU and CLAAlways mapped to both the CPU and CLA

Message RAMs

Contains variables and coefficients used by the CLA program codeMapped to the CPU at resetInitialized by CPU

CLA Data MemoryADC Results RegsePWM (all regs)HRPWM (all regs)Comparator (all regs)

Peripheral Reg Access

Prog RAM Data RAM0 Data RAM1MSG RAMsCPU to CLACLA to CPU

L3 DPSARAM L1 DPSARAM L2 DPSARAM PF0 PF0 & PF1Periph. RegsADC Results

ePWMHRPWM

Comparator

CLA Tasks

CLA Tasks

A Task is similar to an interrupt service routineCLA supports 8 Tasks (Task1-8)A task is started by a peripheral interrupt trigger

Triggers are enabled in the MPISRCSEL1 registerWhen a trigger occurs the CLA begins execution at the associated task vector entry (MVECT1-8) Once a task begins it runs to completion (no nesting)

A task is terminated with an MSTOP instruction

MPERINT1-8

ADCINT1 orEPWM1_INT

ADCINT7 orEPWM7_INT

ADCINT8 orCPU Timer 0

CLA_INT1-8LVF, LUF PIE

C28xCPU

INT11INT12

CLAControl & Execution

Registers

Task Triggers(Peripheral Interrupts)



Software triggering a task

Tasks can also be started by a software triggerusing the CPU

asm(" EALLOW"); // enable protected register access

Cla1Regs.MIFRC.bit.INT4 = 1; // start task 4

asm(" EDIS"); // disable protected register access

Method #1: Write to Interrupt Force Register (MIFRC) register

INT2INT3INT4INT5INT6INT7INT8 INT10123456715 - 8

reserved

Method #2: Use IACK instruction

asm(" IACK #0x0008"); // set bit 4 in MIFR to start task 4

More efficient – does not require EALLOWNote: Use of IACK requires Cla1Regs.MCTL.bit.IACKE = 1

Control and Execution Registers

CLA Control and Execution Registers

ADCINT1ePWM1_INT

S/W trigger1

ADCINT8CPU Timer 0

S/W trigger0

MIFR MIER

MPISRCSEL1

CLACore

CLA Program Bus CLA Data BusProgramMemory

DataMemory

MMEMCFG

MVECT1-8MPC

MAR0MAR1

CLA_INT1-8LVF, LUF

MR0MR1MR2MR3

PIE C28xCPU

INT11INT12

MPISRCSEL1 – Peripheral Interrupt Source Select (Task 1-8)MVECT1-8 – Task Interrupt Vector (MVECT1/2/3/4/5/6/7/8)MMEMCFG – Memory Map Configuration (RAM1E, RAM0E, PROGE)MPC – 12-bit Program Counter (initialized by appropriate MVECTx register)MR0-3 – CLA Floating-Point 32-bit Result RegistersMAR0-1 – CLA Auxiliary Registers



CLA Registers

CLA RegistersCla1Regs.register (lab file: Cla.c)

MCTL Control RegisterMMEMCFG Memory Configuration RegisterMPISRCSEL1 Peripheral Interrupt Source Select 1 RegisterMIFR Interrupt Flag RegisterMIER Interrupt Enable RegisterMIFRC Interrupt Force RegisterMICLR Interrupt Flag Clear RegisterMIOVF Interrupt Overflow Flag RegisterMICLROVF Interrupt Overflow Flag Clear RegisterMIRUN Interrupt Run Status RegisterMVECTx Task x Interrupt Vector (x = 1-8)MPC CLA 12-bit Program CounterMARx CLA Auxiliary Register x (x = 0-1)MRx CLA Floating-Point 32-bit Result Register (x = 0-3)MSTF CLA Floating-Point Status Register

Register Description

CLA Control RegisterCla1Regs.MCTL

HARDRESETIACKE SOFTRESETreserved15 - 3 02 1

Hard Reset0 = no effect1 = CLA reset

(registers setto default state)

Soft Reset0 = no effect1 = CLA reset

(stop current task)

IACK Enable0 = CPU IACK instruction ignored1 = CPU IACK instruction triggers a task



CLA Memory Configuration RegisterCla1Regs.MMEMCFG

PROGE015 - 6

reserved RAM1E RAM0E45 2 - 1

reserved

CLA Program Space Enable0 = mapped to CPU program and data space1 = mapped to CLA program space

CLA Data RAM1 / RAM0 Enable0 = mapped to CPU program and data space1 = mapped to CLA data space

CLA Peripheral Interrupt SourceSelect 1 Register

Cla1Regs.MPISRCSEL1

PERINT8SEL31 - 28 19 - 16

PERINT7SEL PERINT6SEL PERINT5SEL27 - 24 23 - 20

PERINT4SEL15 - 12 3 - 0

PERINT3SEL PERINT2SEL PERINT1SEL11 - 8 7 - 4

Task 1 PeripheralInterrupt Input000 = ADCINT1010 = ePWM1xx1 = no source




Task 8 PeripheralInterrupt Input000 = ADCINT8010 = CPU Timer 0xx1 = no source




000 = DefaultNote: select xx1 (no source) if task is generated by software



CLA Interrupt Enable RegisterCla1Regs.MIER

INT2INT3INT4INT5INT6INT7INT8 INT10123456715 - 8

reserved

#include “DSP2803x_Device.h”

Cla1Regs.MIER.bit.INT2 = 1; //enable Task 2 interrupt

Cla1Regs.MIER.all = 0x0028; //enable Task 6 and 4 interrupts

0 = task interrupt disable (default)1 = task interrupt enable

CLA Initialization

CLA Initialization

1. Copy CLA task code from flash to CLA program RAM

2. Initialize CLA data RAMs, as neededPopulate with data coefficients, constants, etc.

3. Configure the CLA registersEnable the CLA clock (PCLKCR3 register)

Populate the CLA task interrupt vectors (MVECT1-8 registers)

Select the desired task interrupt sources (PERINT1SEL register)

If desired, enable IACK to start task using software (avoids EALLOW)

Map CLA program RAM and data RAMs to CLA space

4. Configure desired CLA task completion interrupts in the PIE

5. Enable CLA tasks triggers in the MIER register

6. Initialize the ePWM and/or ADC to trigger the CLA tasks

CLA initialization is performed by the CPU in C code(typically done with the Peripheral Register Header Files)

Data is passed between the CLA and CPU via message RAMs



Enabling CLA Support in CCS

Note: You must be using a C28x Piccolo device that has the Control Law Accelerator!

In the project build options, select: ‘cla0 (From Device Type 0)’

This is required in order to assemble CLA code

CLA support requires codegen tools v5.2.0 or later

CLA Task Programming

CLA Task Programming

CLA tasks are written in assembly codeSame instruction format as the C28x and C28x+FPU

Destination operand is always on the leftSame mnemonics as C28x+FPU but with a leading “M”

CPU: MPY ACC, T, loc16

FPU: MPYF32 R0H, R1H, R2H

CLA: MMPYF32 MR0, MR1, MR2

Destination Source Operands



CLA Instruction Set

CLA Instruction Overview

1MNOPNo Operation1MSTOPHalt Code or End Task1MEALLOWWrite Protection Enable/Disable1MLSR32 MRa,#SHIFTInteger Shifts1MSUB32 MRa,MRb,MRcInteger Add and Subtract1MAND32 MRa,MRb,MRcInteger Bitwise AND, OR, XOR

1-7MBCNDD 16bitdest {,CNDF}Branch/Call/Return Conditional Delayed

1MMOV16 MAR,mem16Load/Store Auxiliary Register1MMOV16 MRa,mem16Integer Load/Store

1MMOV32 MSTF,mem32Store/Load MSTF

1MMPYF32 MRa,MRb,MRcMultiply, Add, Subtract1MEINVF32 MRa,MRb1/X (16-bit Accurate)1MEISQRTF32 MRa,MRb1/Sqrt(x) (16-bit Accurate)

1MUI16TOF32 MRa,mem16Unsigned Integer to Float1MI32TOF32 MRa,mem32Integer to Float1MF32TOI16R MRa,MRbFloat to Integer & Round1MF32TOI32 MRa,MRbFloat to Integer

1MCMPF32 MRa,MRbCompare, Min, Max1MABSF32 MRa,MRbAbsolute, Negative Value

1MMOVD32 MRa,mem32Load with Data MoveMMOV32 mem32,MRa

MMOV32 MRa,mem32{,CONDF}Example

1Load (Conditional)1Store

CyclesType

CLA Parallel Instructions

Multiply, Add, Subtract, MAC& Parallel Load

Multiply, Add, Subtract& Parallel Store

Multiply& Parallel Add/Subtract

Instruction

1MADDF32 MRa,MRb,MRc

|| MMOV32 mem32,MRe

1MMPYF32 MRa,MRb,MRc

|| MSUBF32 MRd,MRe,MRf


|| MMOV32 MRe, mem32

CyclesExample

Both operations complete in a single cycle

Parallel bars indicate a parallel instructionParallel instructions operate as a single instruction with a single opcode and performs two operations

Example: Add + Parallel Store

MADDF32 MR3, MR3, MR1|| MMOV32 @_Var, MR3



CLA Addressing Modes

CLA Addressing ModesCLA has two addressing modes

Both modes can access the low 64Kw of memory:All of the CLA data spaceBoth message RAMsShared peripheral registers

There is no stack pointer or data page pointerDirect Addressing Mode:

Populates opcode field with 16-bit address of the variable

Example 1: MMOV32 MR1, @_VarAExample 2: MMOV32 MR1, @_EPwm1Regs.CMPA.all

Indirect Addressing with 16-bit Post Increment:Uses the address in MAR0 or MAR1 to access memoryAfter the read or write MAR0/MAR1 is incremented by #Imm16

Example 1: MMOV32 MR0, *MAR0[2]++Example 2: MMOV32 MR1, *MAR1[-2]++

CLA Code Example

CLA Code Example (1 of 2)

.cdecls "Lab.h"

.sect "Cla1Prog"

_Cla1Prog_Start

_Cla1Task1: ; FIR filter

MUI16TOF32 MR2, @_AdcResult.ADCRESULT0

MMPYF32 MR2, MR1, MR0

MADDF32 MR3, MR3, MR2

MF32TOUI16 MR2, MR3

MMOV16 @_ClaFilteredOutput, MR2

MSTOP ; End of task

;-------------------------------------

_Cla1Task2:

MSTOP

;-------------------------------------

_Cla1Task3:

MSTOP

ClaTasks.asm

.cdecls directive used to include the C header file in the CLA assembly file

.sect directive used to place CLA assembly code in its own section

C Peripheral Register Header File references can be used in CLA assembly code

MSTOP instruction used at the end of the task

CLA assembly and C28 C-code reside in the same project



CLA Code Example (2 of 2)

#include "DSP2803x_Device.h"

extern Uint32 Cla1Prog_Start;

extern Uint32 Cla1Task1;



Lab.h

#include "Lab.h"

// Symbols used to calculate vector address

Cla1Regs.MVECT1 =(Uint16)((Uint32)&Cla1Task1

(Uint32)&Cla1Prog_Start);

Cla1Regs.MVECT2 =(Uint16)((Uint32)&Cla1Task2 -

(Uint32)&Cla1Prog_Start);

Cla.c

DSP2803x_Device.h defines register bit field structures

Symbols in header file that are defined in the CLA assembly file are made global (by the .cdecls in Cla.asm) and are usable in C

CLA Code Debugging

CLA Code Debugging

1. Insert a breakpoint in CLA codeInsert MDEBUGSTOP instruction to halt CLA and then rebuild/reload

2. Enable CLA breakpointsEnable CLA breakpoints in the debugger

3. Start the taskDone by peripheral interrupt, software (IACK) or MIFRC registerCLA executes instructions until MDEBUGSTOPMPC will the have address of MDEBUGSTOP instruction

4. Single step the CLA codeOnce halted, single step the CLA codeCan also run to the next MDEBUGSTOP or to the end of taskIf another task is pending it will start at end of previous task

5. Disable CLA breakpoints, if desired

• The CLA can halt, single-step and run independently from the CPU• Both the CLA and CPU are debugged from the same JTAG port

• CLA single step – CLA pipeline is clocked only one cycle and then frozen• CPU single step – CPU pipeline is flushed for each single step


Lab 9: CLA Floating-Point FIR Filter

Lab 9: CLA Floating-Point FIR Filter Objective

The objective of this lab is to become familiar with operation of the CLA. In the previous lab, the CPU was used to filter the ePWM1A generated 2 kHz, 25% duty cycle symmetric PWM waveform. In this lab, the PWM waveform will be filtered using the CLA. The CLA will directly read the ADC result register and a task will run a low-pass FIR filter on the sampled waveform. The filtered result will be stored in a circular memory buffer. Note that the CLA is operating concurrently with the CPU. As an operational test, the filtered and unfiltered waveforms will be displayed using the graphing feature of Code Composer Studio.



ADCRESULT0

ePWM2

connectorwire

ADCINA0

...

datamemory

poin

ter

rew

ind

Display using CCS

TB CounterCompare

Action Qualifier

ePWM1

ePWM2 triggering ADC on period match using SOCA trigger every 20 µs (50 kHz)

CLA_Cla1Task1_Cla1Task2

_Cla1Task8

Procedure


on Project Open… and look in C:\C28x\Labs\Lab9. All Build Options have been configured the same as the previous lab. The files used in this lab are: Adc.c EPwm_7_8_9_10_12.cCla_9.c Filter.cClaTasks.asm Gpio.cCodeStartBranch.asm Lab_9.cmdDefaultIsr_9_10.c Main_9.cDelayUs.asm PieCtrl_5_6_7_8_9_10.cDSP2803x_GlobalVariableDefs.c PieVect_5_6_7_8_9_10.cDSP2803x_Headers_nonBIOS.cmd SysCtrl.cECap_7_8_9_10_12.c Watchdog.c



Enabling CLA Support in CCS 2. Open the Build Options and select the Compiler tab. In the Basic Category set the

Specify CLA Support to cla0 (From Device Type 0). This is needed to assemble CLA code. Then select OK to save the Build Options.

Inspect Lab_9.cmd 3. Open and inspect Lab_9.cmd. Notice that a section called “Cla1Prog” is being

linked to L3DPSARAM. This section links the CLA program tasks (assembly code) to the CPU memory space. This memory space will be remapped to the CLA memory space during initialization. Also, notice the two message RAM sections used to pass data between the CPU and CLA.

Setup CLA Initialization During the CLA initialization, the CPU memory block L3DPSARAM needs to be configured as CLA program memory. This memory space contains the CLA Task routines, which are coded in assembly. The CLA Task 1 has been configured to run an FIR filter. The CLA needs to be configured to start Task 1 on the ADCINT1 interrupt trigger. The next section will setup the PIE interrupt for the CLA.

4. Open ClaTasks.asm and notice that the .cdecls directive is being used to include the C header file in the CLA assembly file. Therefore, we can use the Peripheral Register Header File references in the CLA assembly code. Next, notice Task 1 has been configured to run an FIR filter. Within this code special instructions have been used to convert the ADC result integer (i.e. the filter input) to floating-point and the floating-point filter output back to integer.

5. Edit Cla_9.c to implement the CLA operation as described in the objective for this lab exercise. Configure the L3DPSARM memory block to be mapped to CLA program memory space. Set Task 1 peripheral interrupt source to ADCINT1 and set the other Task peripheral interrupt source inputs to no source. Enable CLA Task 1 interrupt.

6. Open Main_9.c and add a line of code in main() to call the InitCla() function. There are no passed parameters or return values. You just type

InitCla();

at the desired spot in main().

Setup PIE Interrupt for CLA Recall that ePWM2 is triggering the ADC at a 50 kHz rate. In the previous lab exercise, the ADC generated an interrupt to the CPU, and the CPU implemented the FIR filter in the ADC ISR. For this lab exercise, the ADC is instead triggering the CLA, and the CLA will directly read the ADC result register and run a task implementing an FIR filter. The CLA will generate an interrupt to the CPU, which will store the filtered results to a circular buffer implemented in the CLA ISR.



7. Edit Adc.c to comment out the code used to enable ADCINT1 interrupt in PIE group 1. This is no longer being used. The CLA interrupt will be used instead.

8. Using the “PIE Interrupt Assignment Table” find the location for the CLA Task 1 interrupt “CLA1_INT1” and fill in the following information:



9. Modify the end of Cla_9.c to do the following: - Enable the "CLA1_INT1" interrupt in the PIE (Hint: use the PieCtrlRegs structure) - Enable the appropriate core interrupt in the IER register

10. Open and inspect DefaultIsr_9_10.c. Notice that this file contains the CLA interrupt service routine. Save and close all modified files.

Build and Load 11. Click the “Build” button to build and load the project.

Run the Code – Test the CLA Operation

Note: For the next step, check to be sure that the jumper wire connecting PWM1A (pin # GPIO-00) to ADCINA0 (pin # ADC-A0) is in place on the Docking Station.

12. Run the code in real-time mode using the GEL function: GEL Realtime Emulation Control Run_Realtime_with_Reset, and watch the memory window update. Verify that the ADC result buffer contains updated values.

13. Setup a dual-time graph of the filtered and unfiltered ADC results buffer. Click: View Graph Time/Frequency… and set the following values:



Display Type Dual Time

Start Address – upper display AdcBufFiltered

Start Address – lower display AdcBuf






14. The graphical display should show the filtered PWM waveform in the upper display and the unfiltered waveform in the lower display. You should see that the results match the previous lab exercise.


End of Exercise


System Design

Introduction This module discusses various aspects of system design. Details of the emulation and analysis block along with JTAG will be explored. Flash memory programming and the Code Security Module will be described.


Emulation and Analysis Block

Flash Configuration and Memory Performance

Flash Programming


C2000 Piccolo Workshop - System Design 10 - 1

Module Topics

Module Topics System Design ...........................................................................................................................................10-1

Module Topics........................................................................................................................................10-2 Emulation and Analysis Block ...............................................................................................................10-3 Flash Configuration and Memory Performance....................................................................................10-6 Flash Programming ...............................................................................................................................10-9 Code Security Module (CSM) ..............................................................................................................10-11 Lab 10: Programming the Flash..........................................................................................................10-14

10 - 2 C2000 Piccolo Workshop - System Design


Emulation and Analysis Block JTAG Emulation System

(based on IEEE 1149.1 Boundary Scan Standard)

HEADER

System Under Test

SCAN IN

SCAN OUTEmulator

Pod

TMS320C2000

Some Available Emulators

XDS510 CLASS -BlackHawk: USB2000Signum System: JTAGjet-TMS-C2000Spectrum Digital: XDS510LC

XDS100 CLASS -BlackHawk: USB100Olimex: TMS320-JTAG-USBSpectrum Digital: XDS100TI: TMDSEMU100U-14T

These emulators are C2000 specific, and are much lower cost than emulators that support all TI MCU/DSP platforms (although those can certainly be used)

These emulators are much slower than the ones listed above, but are also available at a lower cost than XDS510 class and are NOT C2000 specific

Emulator Connections to the Device

TRST

TMS

TDI

TDO

TCK

EMU0

EMU1

TRST

TMS

TDI

TDO

TCK

TCK_RET

13

14

2

1

3

7

11

9GND

PD

Vcc (3.3 V)

GND

GND

GND

GND

GND

5

4

6

8

10

12

Vcc (3.3 V)

TMS320F2803x Emulator Header

= If distance between device and header is greater than 6 inches

GND



On-Chip Emulation Analysis Block: Capabilities

Two hardware analysis units can be configured to provide any one of the following advanced debug features:

Halt program execution after a specific value is written to a variable

1 Address Watchpoint with Data

Halt on a specified instruction only after some other specific routine has executed

1 Pair Chained Breakpoints

Halt on a specified instruction(for debugging in Flash)

2 Hardware Breakpoints

A memory location is getting corrupted; halt the processor when any value is written to this location

2 Address Watchpoints

Debug ActivityAnalysis Configuration

⇒

⇒

⇒

⇒

On-Chip Emulation Analysis Block: Hardware Breakpoints

Symbolic or numeric address

Mask value for specifying address ranges

Chained breakpoint selection



On-Chip Emulation Analysis Block: Watchpoints

Symbolic or numeric address

Mask value for specifying address ranges

Bus selection

Address with Data selection

On-Chip Emulation Analysis Block: Online Stack Overflow Detection

Emulation analysis registers are accessible to code as well!Configure a watchpoint to monitor for writes near the end of the stackWatchpoint triggers maskable RTOSINT interruptWorks with DSP/BIOS and non-DSP/BIOS

See TI application report SPRA820 for implementation details

Data Memory

Monitor for data writes in region near the end of the stack

Region of memory

occupied by the stack

Stack grows towards higher memory addresses



Flash Configuration and Memory Performance Basic Flash Operation

Flash is arranged in pages of 128 wordsWait states are specified for consecutive accesses within a page, and random accesses across pagesOTP has random access onlyMust specify the number of SYSCLKOUT wait-states;Reset defaults are maximum value (15)Flash configuration code should not be run from the Flash memory

FlashRegs.FBANKWAIT RANDWAITreserved

15 04 38 7

PAGEWAIT reserved

12 11

FlashRegs.FOTPWAIT OTPWAITreserved

15 05 4

*** Refer to the F2803x datasheet for detailed numbers ***For 60 MHz, PAGEWAIT = 2, RANDWAIT = 2, OTPWAIT = 3

16 or 32 dispatched

16

64

Aligned 64-bit fetch

2-level deep fetch buffer

64

C28x Core decoder unit

Speeding Up Code Execution in FlashFlash Pipelining (for code fetch only)

Flash Pipeline Enable0 = disable (default)1 = enable

ENPIPEreserved15 01FlashRegs.FOPT.bit.ENPIPE = 1;



Code Execution Performance

Assume 60 MHz SYSCLKOUT, 16-bit instructions(80% of instructions are 16 bits wide – Rest are 32 bits)

Internal RAM: 60 MIPSFetch up to 32-bits every cycle 1 instruction/cycle * 60 MHz = 60 MIPS

Flash (w/ pipelining): 60 MIPSRANDWAIT = 2Fetch 64 bits every 3 cycles, but it will take 4 cycles to execute them

4 instructions/4 cycles * 60 MHz = 60 MIPSRPT will increase this; PC discontinuity will degrade thisBenchmarking in control applications has shown actual performance of about 54 MIPS

Data Access Performance

Internal RAM has best data performance – put time critical data hereFlash performance usually sufficient for most constants and tablesNote that the flash instruction fetch pipeline will also stall during a flash data access

Memory 16-bit access 32-bit access Notes(words/cycle) (words/cycle)

Internal RAM 1 1

Flash 0.33 0.33 RANDWAIT = 2Flash is read only!

Assume 60 MHz SYSCLKOUT



Other Flash Configuration RegistersFlashRegs.name

Address Name Description0x00 0A80 FOPT Flash option register0x00 0A82 FPWR Flash power modes registers0x00 0A83 FSTATUS Flash status register0x00 0A84 FSTDBYWAIT Flash sleep to standby wait register0x00 0A85 FACTIVEWAIT Flash standby to active wait register0x00 0A86 FBANKWAIT Flash read access wait state register0x00 0A87 FOTPWAIT OTP read access wait state register

FPWR: Save power by putting Flash/OTP to ‘Sleep’ or ‘Standby’mode; Flash will automatically enter active mode if a Flash/OTPaccess is made FSTATUS: Various status bits (e.g. PWR mode)FSTDBYWAIT, FACTIVEWAIT: Specify # of delay cycles during wake-up from sleep to standby, and from standby to active, respectively. The delay is needed to let the flash stabilize. Leave these registers set to their default maximum value.

See the “TMS320x2803x Piccolo System Control and Interrupts Reference Guide,” SPRUGL8, for more information


Flash Programming

Flash Programming Flash Programming Basics

The DSP CPU itself performs the flash programmingThe CPU executes Flash utility code from RAM that reads the Flash data and writes it into the FlashWe need to get the Flash utility code and the Flash data into RAM

FLASH CPU

RAM

TMS320F2803x

JTAGEmulator

SPI

Flash Utility Code

Flash Data I2C

ROM

Boot

load

er

CAN

SCIRS232

GPIO

Flash Programming BasicsSequence of steps for Flash programming:

Minimum Erase size is a sector (4Kw or 8Kw)Minimum Program size is a bit!Important not to lose power during erase step: If CSM passwords happen to be all zeros, the CSM will be permanently locked!Chance of this happening is quite small! (Erase step is performed sector by sector)

1. Erase - Set all bits to zero, then to one2. Program - Program selected bits with zero3. Verify - Verify flash contents

Algorithm Function


Flash Programming

Flash Programming UtilitiesJTAG Emulator Based

Code Composer Studio Plug-inBlackHawk Flash utilities (requires Blackhawk emulator)Elprotronic FlashPro2000 Spectrum Digital SDFlash JTAG (requires SD emulator)Signum System Flash utilities (requires Signum emulator)

SCI Serial Port Bootloader BasedCode-Skin (http://www.code-skin.com)Elprotronic FlashPro2000

Production Test/Programming Equipment BasedBP Micro programmerData I/O programmer

Build your own custom utilityCan use any of the ROM bootloader methodsCan embed flash programming into your applicationFlash API algorithms provided by TI

* TI web has links to all utilities (http://www.ti.com/c2000)

Code Composer Studio Flash Plug-In



Code Security Module (CSM) Code Security Module (CSM)

Data reads and writes from restricted memory are only allowed for code running from restricted memoryAll other data read/write accesses are blocked:JTAG emulator/debugger, ROM bootloader, code running in external memory or unrestricted internal memory

Access to the following on-chip memory is restricted:


User OTP (1Kw)

ADC / OSC cal. data

L0 SARAM (2Kw)

reserved

reservedDualMapped

FLASH (64Kw)PASSWORDS (8w)

reserved

0x0080000x0088000x008C00

0x00A0000x009000

0x3D78000x3D7C000x3D7C800x3D80000x3E80000x3F7FF80x3F80000x3F8800

Flash Registers0x000A80

CSM Password

128-bit user defined password is stored in Flash

128-bit KEY registers are used to lock and unlock the device

Mapped in memory space 0x00 0AE0 – 0x00 0AE7Registers “EALLOW” protected

0x3F7FF8 - 0x3F7FFF

CSM PasswordLocations (PWL)

FLASH (64Kw)

0x3E8000

128-Bit Password0x3F7FF8



CSM RegistersAddress Name Description0x00 0AE0 KEY0 Low word of 128-bit Key register0x00 0AE1 KEY1 2nd word of 128-bit Key register0x00 0AE2 KEY2 3rd word of 128-bit Key register0x00 0AE3 KEY3 4th word of 128-bit Key register0x00 0AE4 KEY4 5th word of 128-bit Key register0x00 0AE5 KEY5 6th word of 128-bit Key register0x00 0AE6 KEY6 7th word of 128-bit Key register0x00 0AE7 KEY7 High word of 128-bit Key register0x00 0AEF CSMSCR CSM status and control register

Key Registers – accessible by user; EALLOW protected

Address Name Description0x3F 7FF8 PWL0 Low word of 128-bit password0x3F 7FF9 PWL1 2nd word of 128-bit password0x3F 7FFA PWL2 3rd word of 128-bit password0x3F 7FFB PWL3 4th word of 128-bit password0x3F 7FFC PWL4 5th word of 128-bit password0x3F 7FFD PWL5 6th word of 128-bit password0x3F 7FFE PWL6 7th word of 128-bit password0x3F 7FFF PWL7 High word of 128-bit password

PWL in memory – reserved for passwords only

Locking and Unlocking the CSM

The CSM is always locked after resetTo unlock the CSM:

Perform a dummy read of each PWL (passwords in the flash)Write the correct password to each KEY register

Passwords are all 0xFFFF on new devicesWhen passwords are all 0xFFFF, only a read of each PWL is required to unlock the deviceThe bootloader does these dummy reads and hence unlocks devices that do not have passwords programmed



CSM Caveats

Never program all the PWL’s as 0x0000Doing so will permanently lock the CSM

Flash addresses 0x3F7F80 to 0x3F7FF5, inclusive, must be programmed to 0x0000 to securely lock the CSM Remember that code running in unsecured RAM cannot access data in secured memory

Don’t link the stack to secured RAM if you have any code that runs from unsecured RAM

Do not embed the passwords in your code!Generally, the CSM is unlocked only for debugCode Composer Studio can do the unlocking

CSM Password Match Flow

Flash device secure after

reset or runtime

Do dummy reads of PWL 0x3F 7FF8 – 0x3F 7FFF

Start Device permanently locked

Device unlockedUser can access on-chip secure memory

Write password to KEY registers 0x00 0AE0 – 0x00 0AE7

(EALLOW) protected

Correct password?

Is PWL = all Fs?

Is PWL = all 0s?

Yes

Yes

Yes

No

No

No


Lab 10: Programming the Flash

Lab 10: Programming the Flash Objective

The objective of this lab is to program and execute code from the on-chip flash memory. The TMS320F28035 device has been designed for standalone operation in an embedded system. Using the on-chip flash eliminates the need for external non-volatile memory or a host processor from which to bootload. In this lab, the steps required to properly configure the software for execution from internal flash memory will be covered.


Objective:Program system into Flash MemoryLearn use of CCS Flash Plug-inDO NOT PROGRAM PASSWORDS

ADCRESULT0

ePWM2

connectorwire

TB CounterCompare

Action Qualifier

ePWM1ADCINA0



...

datamemory

poin

ter

rew

ind

Display using CCS


_Cla1Task8

Procedure

Project File 1. A project named Lab10.pjt has been created for this lab. Open the project by

clicking on Project Open… and look in C:\C28x\Labs\Lab10. All Build Options have been configured the same as the previous lab. The files used in this lab are: Adc.c Filter.cCla_10_12.c Flash.cClaTasks.asm Gpio.cCodeStartBranch.asm Lab_10.cmdDefaultIsr_9_10.c Main_10.cDelayUs.asm Passwords.asmDSP2803x_GlobalVariableDefs.c PieCtrl_5_6_7_8_9_10.cDSP2803x_Headers_nonBIOS.cmd PieVect_5_6_7_8_9_10.cECap_7_8_9_10_12.c SysCtrl.cEPwm_7_8_9_10_12.c Watchdog.c



Link Initialized Sections to Flash Initialized sections, such as code and constants, must contain valid values at device power-up. Stand-alone operation of an F28035 embedded system means that no emulator is available to initialize the device RAM. Therefore, all initialized sections must be linked to the on-chip flash memory.

Each initialized section actually has two addresses associated with it. First, it has a LOAD address which is the address to which it gets loaded at load time (or at flash programming time). Second, it has a RUN address which is the address from which the section is accessed at runtime. The linker assigns both addresses to the section. Most initialized sections can have the same LOAD and RUN address in the flash. However, some initialized sections need to be loaded to flash, but then run from RAM. This is required, for example, if the contents of the section needs to be modified at runtime by the code.

2. Open and inspect the linker command file Lab_10.cmd. Notice that a memory block named FLASH_ABCDEFGH has been been created at origin = 0x3E8000, length = 0x00FF80 on Page 0. This flash memory block length has been selected to avoid conflicts with other required flash memory spaces. See the reference slide at the end of this lab exercise for further details showing the address origins and lengths of the various memory blocks used.

3. Edit Lab_10.cmd to link the following compiler sections to on-chip flash memory block FLASH_ABCDEFGH:

Compiler Sections

.text

.cinit

.const

.econst

.pinit

.switch

4. In Lab_10.cmd notice that the section named “IQmath” is an initialized section that needs to load to and run from flash. Previously the “IQmath” section was linked to L0SARAM. Edit Lab_10.cmd so that this section is now linked to FLASH_ABCDEFGH. Save your work and close the file.

Copying Interrupt Vectors from Flash to RAM The interrupt vectors must be located in on-chip flash memory and at power-up needs to be copied to the PIE RAM as part of the device initialization procedure. The code that performs this copy is located in InitPieCtrl(). The C-compiler runtime support library contains a memory copy function called memcpy() which will be used to perform the copy.



5. Open and inspect InitPieCtrl() in PieCtrl_5_6_7_8_9_10.c. Notice the memcpy() function used to initialize (copy) the PIE vectors. At the end of the file a structure is used to enable the PIE.

Initializing the Flash Control Registers The initialization code for the flash control registers cannot execute from the flash memory (since it is changing the flash configuration!). Therefore, the initialization function for the flash control registers must be copied from flash (load address) to RAM (run address) at runtime. The memory copy function memcpy() will again be used to perform the copy. The initialization code for the flash control registers InitFlash() is located in the Flash.c file.

6. Add Flash.c to the project.

7. Open and inspect Flash.c. The C compiler CODE_SECTION pragma is used to place the InitFlash() function into a linkable section named “secureRamFuncs”.

8. The “secureRamFuncs” section will be linked using the user linker command file Lab_10.cmd. Open and inspect Lab_10.cmd. The “secureRamFuncs” will load to flash (load address) but will run from L0SARAM (run address). Also notice that the linker has been asked to generate symbols for the load start, load size, and run start addresses.

While not a requirement from a MCU hardware or development tools perspective (since the C28x MCU has a unified memory architecture), historical convention is to link code to program memory space and data to data memory space. Therefore, notice that for the L0SARAM memory we are linking “secureRamFuncs” to, we are specifiying “PAGE = 0” (which is program memory).

9. Open and inspect Main_10.c. Notice that the memory copy function memcpy() is being used to copy the section “secureRamFuncs”, which contains the initialization function for the flash control registers.

10. Add a line of code in main() to call the InitFlash() function. There are no passed parameters or return values. You just type

InitFlash();

at the desired spot in main().

Code Security Module and Passwords The CSM module provides protection against unwanted copying (i.e. pirating!) of your code from flash, OTP memory, and the L0, L1, L2 and L3 RAM blocks. The CSM uses a 128-bit password made up of 8 individual 16-bit words. They are located in flash at addresses 0x3F7FF8 to 0x3F7FFF. During this lab, dummy passwords of 0xFFFF will be used – therefore only dummy reads of the password locations are needed to unsecure the CSM. DO NOT PROGRAM ANY REAL PASSWORDS INTO THE DEVICE. After development, real passwords are typically



placed in the password locations to protect your code. We will not be using real passwords in the workshop.

The CSM module also requires programming values of 0x0000 into flash addresses 0x3F7F80 through 0x3F7FF5 in order to properly secure the CSM. Both tasks will be accomplished using a simple assembly language file Passwords.asm.

11. Add Passwords.asm to the project.

12. Open and inspect Passwords.asm. This file specifies the desired password values (DO NOT CHANGE THE VALUES FROM 0xFFFF) and places them in an initialized section named “passwords”. It also creates an initialized section named “csm_rsvd” which contains all 0x0000 values for locations 0x3F7F80 to 0x3F7FF5 (length of 0x76).

13. Open Lab_10.cmd and notice that the initialized sections for “passwords” and “csm_rsvd” are linked to memories named PASSWORDS and CSM_RSVD, respectively.

Executing from Flash after Reset The F28035 device contains a ROM bootloader that will transfer code execution to the flash after reset. When the boot mode selection is set for “Jump to Flash” mode, the bootloader will branch to the instruction located at address 0x3F7FF6 in the flash. An instruction that branches to the beginning of your program needs to be placed at this address. Note that the CSM passwords begin at address 0x3F7FF8. There are exactly two words available to hold this branch instruction, and not coincidentally, a long branch instruction “LB” in assembly code occupies exactly two words. Generally, the branch instruction will branch to the start of the C-environment initialization routine located in the C-compiler runtime support library. The entry symbol for this routine is _c_int00. Recall that C code cannot be executed until this setup routine is run. Therefore, assembly code must be used for the branch. We are using the assembly code file named CodeStartBranch.asm.

14. Open and inspect CodeStartBranch.asm. This file creates an initialized section named “codestart” that contains a long branch to the C-environment setup routine. This section needs to be linked to a block of memory named BEGIN_FLASH.

15. In the earlier lab exercises, the section “codestart” was directed to the memory named BEGIN_M0. Edit Lab_10.cmd so that the section “codestart” will be directed to BEGIN_FLASH. Save your work and close the opened files.

On power up the reset vector will be fetched and the ROM bootloader will begin execution. If the emulator is connected, the device will be in emulator boot mode and will use the EMU_KEY and EMU_BMODE values in the PIE RAM to determine the bootmode. This mode was utilized in an earlier lab. In this lab, we will be disconnecting the emulator and running in stand-alone boot mode (but do not disconnect the emulator yet!). The bootloader will read the OTP_KEY and OTP_BMODE values from their locations in the OTP. The behavior when these values have not been programmed (i.e., both 0xFFFF) or have been set to invalid values is boot to flash bootmode.



Initializing the CLA Previously, the named section “Cla1Prog” containing the CLA program tasks was linked directly to the CPU memory block L3DPSARAM for both load and run purposes. At runtime, all the code did was map the L3DPSARAM block to the CLA program memory space during CLA initialization. For an embedded application, the CLA program tasks are linked to load to flash and run from RAM. At runtime, the CLA program tasks must be copied from flash to L3DPSARAM. The memory copy function memcpy() will once again be used to perform the copy. After the copy is performed, the L3DPSARAM block will then be mapped to CLA program memory space as was done in the earlier lab.

16. Open and inspect Lab_10.cmd. Notice that the named section “Cla1Prog” will now load to flash (load address) but will run from L3DPSARAM (run address). The linker will also be used to generate symbols for the load start, load size, and run start addresses.

17. Open Cla_10_12.c and notice that the memory copy function memcpy() is being used to copy the CLA program code from flash to L3DPSARAM using the symbols generated by the linker. Just after the copy the Cla1Regs structure is used to configure the L3DPSARAM block as CLA program memory space. Close the inspected files.

Build – Lab.out 18. At this point we need to build the project, but not have CCS automatically load it since

CCS cannot load code into the flash (the flash must be programmed)! On the menu bar click: Option Customize… and select the “Program/Project CIO” tab. Uncheck “Load Program After Build”.

CCS has a feature that automatically steps over functions without debug information. This can be useful for accelerating the debug process provided that you are not interested in debugging the function that is being stepped-over. While single-stepping in this lab exercise we do not want to step-over any functions. Therefore, select the “Debug Properties” tab. Uncheck “Step over functions without debug information when source stepping”, then click OK.

19. Click the “Build” button to generate the Lab.out file to be used with the CCS Flash Plug-in.

CCS Flash Plug-in 20. Open the Flash Plug-in tool by clicking:

Tools F28xx On-Chip Flash Programmer

21. A Clock Configuration window may open. If needed, in the Clock Configuration window set “OSCCLK (MHz):” to 10, “DIVSEL:” to /2, and “PLLCR Value:” to 12. Then click OK. In the next Flash Programmer Settings window confirm that the selected DSP device to program is F28035 and all options have been checked. Click OK.



22. The CCS Flash Programmer uses the Piccolo™ 10 MHz internal oscillator as the device clock during programming. Confirm the “Clock Configuration” in the upper left corner has the OSCCLK set to 10 MHz, the DIVSEL set to /2, and the PLLCR value set to 12. Recall that the PLL is divided by two, which gives a SYSCLKOUT of 60 MHz.

23. Confirm that all boxes are checked in the “Erase Sector Selection” area of the plug-in window. We want to erase all the flash sectors.

24. We will not be using the plug-in to program the “Code Security Password”. Do not modify the Code Security Password fields. They should remain as all 0xFFFF.

25. In the “Operation” block, notice that the “COFF file to Program/Verify” field automatically defaults to the current .out file. Check to be sure that “Erase, Program, Verify” is selected. We will be using the default wait states, as shown on the slide in this module. The selection for wait-states only affects the verify step, and makes little noticeable difference even if you reduce the wait-states.

26. Click “Execute Operation” to program the flash memory. Watch the programming status update in the plug-in window.

27. After successfully programming the flash memory, close the programmer window.

Running the Code – Using CCS 28. In order to effectively debug with CCS, we need to load the symbolic debug information

(e.g., symbol and label addresses, source file links, etc.) so that CCS knows where everything is in your code. Click:

File Load Symbols Load Symbols Only…

and select Lab10.out in the Debug folder.

29. Reset the CPU. The program counter should now be at 0x3FF8A1, which is the start of the bootloader in the Boot ROM.

30. Under GEL on the menu bar click: EMU Boot Mode Select EMU_BOOT_FLASH. This has the debugger load values into EMU_KEY and EMU_BMODE so that the bootloader will jump to "FLASH" at 0x3F7FF6.

31. Single-Step <F11> through the bootloader code until you arrive at the beginning of the codestart section in the CodeStartBranch.asm file. (Be patient, it will take about 125 single-steps). Notice that we have placed some code in CodeStartBranch.asm to give an option to first disable the watchdog, if selected.

32. Step a few more times until you reach the start of the C-compiler initialization routine at the symbol _c_int00.

33. Now do Debug Go Main. The code should stop at the beginning of your main() routine. If you got to that point succesfully, it confirms that the flash has been



programmed properly, that the bootloader is properly configured for jump to flash mode, and that the codestart section has been linked to the proper address.

34. You can now RUN the CPU, and you should observe the LED on the ControlCARD blinking. Try resetting the CPU, select the EMU_BOOT_FLASH boot mode, and then hitting RUN (without doing all the stepping and the Go Main procedure). The LED should be blinking again.

35. HALT the CPU.

Running the Code – Stand-alone Operation (No Emulator) 36. Close Code Composer Studio.

37. Disconnect the USB cable (emulator) from the Docking Station (i.e. remove power from the ControlCARD).

38. Re-connect the USB cable to the Docking Station to power the ControlCARD. The LED should be blinking, showing that the code is now running from flash memory.

End of Exercise



Lab 10 Reference: Programming the Flash

Flash Memory Section Blocks

PASSWORDSlength = 0x8

page = 0

BEGIN_FLASHlength = 0x2

page = 0

CSM_RSVDlength = 0x76

page = 0

FLASHlength = 0xFF80

page = 0

0x3E 8000

0x3F 7F80

0x3F 7FF6

0x3F 7FF8

origin =

SECTIONS{

codestart :> BEGIN_FLASH, PAGE = 0passwords :> PASSWORDS, PAGE = 0csm_rsvd :> CSM_RSVD, PAGE = 0

}

Lab_10.cmd

Startup Sequence from Flash Memory

0x3F 7FF6

0x3E 8000

0x3F E000

0x3F FFC0

Boot ROM (8Kw)

BROM vector (32w)0x3F F8A1

Boot Code

RESET

0x3F F8A1{SCAN GPIO}

FLASH (64Kw)

Passwords (8w)_c_int00

LB

“rts2800_ml.lib”

“user” code sections

_c_int00

main ( ){

}

2

3

4

5

1

………………


Communications

Introduction The TMS320C28x contains features that allow several methods of communication and data exchange between the C28x and other devices. Many of the most commonly used communications techniques are presented in this module.

The intent of this module is not to give exhaustive design details of the communication peripherals, but rather to provide an overview of the features and capabilities. Once these features and capabilities are understood, additional information can be obtained from various resources such as documentation, as needed. This module will cover the basic operation of the communication peripherals, as well as some basic terms and how they work.


Serial Peripheral Interface (SPI)

Serial Communication Interface (SCI)

Local Interconnect Network (LIN)

Inter-Integrated Circuit (I2C)

Enhanced Controller Area Network (eCAN)

Note: Up to 2 SPI modules (A/B), 1 SCI module (A), 1 LIN module (A), 1 I2C module (A), and 1 eCAN module (A) are available on the F2803x devices

C2000 Piccolo Workshop - Communications 11 - 1

Module Topics

Module Topics Communications.......................................................................................................................................11-1

Module Topics........................................................................................................................................11-2 Communications Techniques .................................................................................................................11-3 Serial Peripheral Interface (SPI) ...........................................................................................................11-4

SPI Registers .....................................................................................................................................11-7 SPI Summary.....................................................................................................................................11-8

Serial Communications Interface (SCI) .................................................................................................11-9 Multiprocessor Wake-Up Modes.....................................................................................................11-11 SCI Registers ...................................................................................................................................11-14 SCI Summary ..................................................................................................................................11-15

Local Interconnect Network (LIN) .......................................................................................................11-16 LIN Message Frame and Data Timing ............................................................................................11-17 LIN Summary..................................................................................................................................11-18

Inter-Integrated Circuit (I2C)..............................................................................................................11-19 I2C Operating Modes and Data Formats .........................................................................................11-20 I2C Summary...................................................................................................................................11-21

Enhanced Controller Area Network (eCAN) .......................................................................................11-22 CAN Bus and Node .........................................................................................................................11-23 Principles of Operation....................................................................................................................11-24 Message Format and Block Diagram...............................................................................................11-25 eCAN Summary ..............................................................................................................................11-26

11 - 2 C2000 Piccolo Workshop - Communications

Communications Techniques

Communications Techniques Several methods of implementing a TMS320C28x communications system are possible. The method selected for a particular design should reflect the method that meets the required data rate at the lowest cost. Various categories of interface are available and are summarized in the learning objective slide. Each will be described in this module.

Synchronous vs. Asynchronous

SynchronousShort distances (on-board)High data rateExplicit clock

Asynchronouslonger distancesLower data rate ( ≈ 1/8 of SPI)Implied clock (clk/data mixed)Economical with reasonable performance

C28x

U2

PCB

Port

C28x

PCB

PortDestination

Serial ports provide a simple, hardware-efficient means of high-level communication between devices. Like the GPIO pins, they may be used in stand-alone or multiprocessing systems.

In a multiprocessing system, they are an excellent choice when both devices have an available serial port and the data rate requirement is relatively low. Serial interface is even more desirable when the devices are physically distant from each other because the inherently low number of wires provides a simpler interconnection.

Serial ports require separate lines to implement, and they do not interfere in any way with the data and address lines of the processor. The only overhead they require is to read/write new words from/to the ports as each word is received/transmitted. This process can be performed as a short interrupt service routine under hardware control, requiring only a few cycles to maintain.

The C28x family of devices have both synchronous and asynchronous serial ports. Detailed features and operation will be described next.



Serial Peripheral Interface (SPI) The SPI module is a synchronous serial I/O port that shifts a serial bit stream of variable length and data rate between the C28x and other peripheral devices. During data transfers, one SPI device must be configured as the transfer MASTER, and all other devices configured as SLAVES. The master drives the transfer clock signal for all SLAVES on the bus. SPI communications can be implemented in any of three different modes:

• MASTER sends data, SLAVES send dummy data

• MASTER sends data, one SLAVE sends data

• MASTER sends dummy data, one SLAVE sends data

In its simplest form, the SPI can be thought of as a programmable shift register. Data is shifted in and out of the SPI through the SPIDAT register. Data to be transmitted is written directly to the SPIDAT register, and received data is latched into the SPIBUF register for reading by the CPU. This allows for double-buffered receive operation, in that the CPU need not read the current received data from SPIBUF before a new receive operation can be started. However, the CPU must read SPIBUF before the new operation is complete of a receiver overrun error will occur. In addition, double-buffered transmit is not supported: the current transmission must be complete before the next data character is written to SPIDAT or the current transmission will be corrupted.

The Master can initiate a data transfer at any time because it controls the SPICLK signal. The software, however, determines how the Master detects when the Slave is ready to broadcast.

SPI Data Flow

SPI Shift Register

SPI Device #1 - Master SPI Device #2 - Slave

Simultaneous transmits and receiveSPI Master provides the clock signal

shift shift

clock

SPI Shift RegisterSPI Shift Register



SPI Block Diagram

SPIRXBUF.15-0

SPIDAT.15-0

SPICLK

SPISOMI

SPISIMO

LSPCLK baudrate

clockpolarity

clockphase

C28x - SPI Master Mode Shown

SPITXBUF.15-0

LSBMSB

TX FIFO_0

TX FIFO_15

RX FIFO_0

RX FIFO_15

SPI Transmit / Receive Sequence 1. Slave writes data to be sent to its shift register (SPIDAT)

2. Master writes data to be sent to its shift register (SPIDAT or SPITXBUF)

3. Completing Step 2 automatically starts SPICLK signal of the Master

4. MSB of the Master’s shift register (SPIDAT) is shifted out, and LSB of the Slave’s shift register (SPIDAT) is loaded

5. Step 4 is repeated until specified number of bits are transmitted

6. SPIDAT register is copied to SPIRXBUF register

7. SPI INT Flag bit is set to 1

8. An interrupt is asserted if SPI INT ENA bit is set to 1

9. If data is in SPITXBUF (either Slave or Master), it is loaded into SPIDAT and transmission starts again as soon as the Master’s SPIDAT is loaded



Since data is shifted out of the SPIDAT register MSB first, transmission characters of less than 16 bits must be left-justified by the CPU software prior to be written to SPIDAT.

Received data is shifted into SPIDAT from the left, MSB first. However, the entire sixteen bits of SPIDAT is copied into SPIBUF after the character transmission is complete such that received characters of less than 16 bits will be right-justified in SPIBUF. The non-utilized higher significance bits must be masked-off by the CPU software when it interprets the character. For example, a 9 bit character transmission would require masking-off the 7 MSB’s.

SPI Data Character Justification

Programmable data length of 1 to 16 bitsTransmitted data of less than 16 bits must be left justified

MSB transmitted first

Received data of less than 16 bits are right justified

User software must mask-off unused MSB’s

11001001XXXXXXXX11001001XXXXXXXX

XXXXXXXX11001001XXXXXXXX11001001

SPIDAT - Processor #1

SPIDAT - Processor #2



SPI Registers

SPI Baud Rate RegisterSpixRegs.SPIBRR

15-7 6-0reserved SPI BIT RATE

SPICLK signal =

LSPCLK(SPIBRR + 1)

LSPCLK4

, SPIBRR = 3 to 127

, SPIBRR = 0, 1, or 2

Need to set this only when in master mode!

Baud Rate Determination: The Master specifies the communication baud rate using its baud rate register (SPIBRR.6-0):

• For SPIBRR = 3 to 127: SPI Baud Rate = )1( +SPIBRR

LSPCLK bits/sec

• For SPIBRR = 0, 1, or 2: SPI Baud Rate = 4

LSPCLK bits/sec

From the above equations, one can compute

Maximum data rate = 25 Mbps @ 100 MHz

Character Length Determination: The Master and Slave must be configured for the same transmission character length. This is done with bits 0, 1, 2 and 3 of the configuration control register (SPICCR.3-0). These four bits produce a binary number, from which the character length is computed as binary + 1 (e.g. SPICCR.3-0 = 0010 gives a character length of 3).



Select SPI RegistersConfiguration Control SpixRegs.SPICCR

Reset, Clock Polarity, Loopback, Character Length

Operation Control SpixRegs.SPICTLOverrun Interrupt Enable, Clock Phase, Interrupt EnableMaster / Slave Transmit enable

Status SpixRegs.SPISTRX Overrun Flag, Interrupt Flag, TX Buffer Full Flag

FIFO Transmit SpixRegs.SPIFFTX

FIFO Receive SpixRegs.SPIFFRXFIFO Enable, FIFO ResetFIFO Over-flow flag, Over-flow ClearNumber of Words in FIFO (FIFO Status)FIFO Interrupt Enable, Interrupt Status, Interrupt ClearFIFO Interrupt Level (Number of Words in FIFO)

Note: refer to the reference guide for a complete listing of registers

SPI Summary

SPI Summary

Synchronous serial communicationsTwo wire transmit or receive (half duplex)Three wire transmit and receive (full duplex)

Software configurable as master or slaveC28x provides clock signal in master mode

Data length programmable from 1-16 bits125 different programmable baud rates


Serial Communications Interface (SCI)

Serial Communications Interface (SCI) The SCI module is a serial I/O port that permits Asynchronous communication between the C28x and other peripheral devices. The SCI transmit and receive registers are both double-buffered to prevent data collisions and allow for efficient CPU usage. In addition, the C28x SCI is a full duplex interface which provides for simultaneous data transmit and receive. Parity checking and data formatting is also designed to be done by the port hardware, further reducing software overhead.

SCI Pin Connections

Transmitter-databuffer register

SCI Device #1

SCIRXD

SCITXD SCITXD

SCIRXD

SCI Device #2

8

Receiver-databuffer register

8

Transmitter-databuffer register

Receivershift register

Transmittershift register

8

Receiver-databuffer register

Receivershift register

Transmittershift register

8

(Full Duplex Shown)

RX FIFO_0

RX FIFO_15

RX FIFO_0

RX FIFO_15

TX FIFO_0

TX FIFO_15

TX FIFO_0

TX FIFO_15



SCI Data Format

This bit present only in Address-bit mode

NRZ (non-return to zero) format

Communications Control Register (ScixRegs.SCICCR)

0 = 1 Stop bit1 = 2 Stop bits

0 = Odd1 = Even

0 = Disabled1 = Enabled

0 = Disabled1 = Enabled

0 = Idle-line mode1 = Addr-bit mode

# of data bits = (binary + 1)e.g. 110b gives 7 data bits

StopBits

Even/OddParity

ParityEnable

LoopbackEnable

Addr/IdleMode

SCIChar2

SCIChar1

SCIChar0

7 6 5 4 3 2 1 0

Start LSB 2 3 4 5 6 7 MSB Addr/Data Parity Stop 1 Stop 2

The basic unit of data is called a character and is 1 to 8 bits in length. Each character of data is formatted with a start bit, 1 or 2 stop bits, an optional parity bit, and an optional address/data bit. A character of data along with its formatting bits is called a frame. Frames are organized into groups called blocks. If more than two serial ports exist on the SCI bus, a block of data will usually begin with an address frame which specifies the destination port of the data as determined by the user’s protocol.

The start bit is a low bit at the beginning of each frame which marks the beginning of a frame. The SCI uses a NRZ (Non-Return-to-Zero) format which means that in an inactive state the SCIRX and SCITX lines will be held high. Peripherals are expected to pull the SCIRX and SCITX lines to a high level when they are not receiving or transmitting on their respective lines.

When configuring the SCICCR, the SCI port should first be held in an inactive state. This is done using the SW RESET bit of the SCI Control Register 1 (SCICTL1.5). Writing a 0 to this bit initializes and holds the SCI state machines and operating flags at their reset condition. The SCICCR can then be configured. Afterwards, re-enable the SCI port by writing a 1 to the SW RESET bit. At system reset, the SW RESET bit equals 0.



SCI Data Timing

Start Bit LSB of Data

MajorityVote

Falling Edge Detected

• Start bit valid if 4 consecutive SCICLK periods of zero bits after falling edge• Majority vote taken on 4th, 5th, and 6th SCICLK cycles

SCIRXD

SCICLK(Internal)

1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 1 2

Note: 8 SCICLK periods per data bit

Multiprocessor Wake-Up Modes

Multiprocessor Wake-Up Modes

Allows numerous processors to be hooked up to the bus, but transmission occurs between only two of themIdle-line or Address-bit modesSequence of Operation1. Potential receivers set SLEEP = 1, which disables RXINT

except when an address frame is received2. All transmissions begin with an address frame3. Incoming address frame temporarily wakes up all SCIs on bus4. CPUs compare incoming SCI address to their SCI address5. Process following data frames only if address matches



Idle-Line Wake-Up Mode

Idle time separates blocks of framesReceiver wakes up when SCIRXD high for 10 or more bit periodsTwo transmit address methods

Deliberate software delay of 10 or more bitsSet TXWAKE bit to automatically leave exactly 11 idle bits

Last Data ST SPST DataSCIRXD/SCITXD

Block of Frames

SP SP Last DataST AddrSP

IdlePeriod10 bits

or greater

IdlePeriod10 bits

or greater

Address framefollows 10 bitor greater idle

1st data frame

SPST Addr

Idle periodsof less than

10 bits

Address-Bit Wake-Up Mode

All frames contain an extra address bitReceiver wakes up when address bit detectedAutomatic setting of Addr/Data bit in frame by setting TXWAKE = 1 prior to writing address to SCITXBUF

Last Data STST DataSCIRXD/SCITXD

Block of Frames

SP SP Last DataST AddrSP

Idle Periodlength of nosignificance

First frame withinblock is Address.

ADDR/DATAbit set to 1

1st data frame

0 1 0 0 SPST Addr 1SP

no additionalidle bits neededbeyond stop bits



The SCI interrupt logic generates interrupt flags when it receives or transmits a complete character as determined by the SCI character length. This provides a convenient and efficient way of timing and controlling the operation of the SCI transmitter and receiver. The interrupt flag for the transmitter is TXRDY (SCICTL2.7), and for the receiver RXRDY (SCIRXST.6). TXRDY is set when a character is transferred to TXSHF and SCITXBUF is ready to receive the next character. In addition, when both the SCIBUF and TXSHF registers are empty, the TX EMPTY flag (SCICTL2.6) is set. When a new character has been received and shifted into SCIRXBUF, the RXRDY flag is set. In addition, the BRKDT flag is set if a break condition occurs. A break condition is where the SCIRXD line remains continuously low for at least ten bits, beginning after a missing stop bit. Each of the above flags can be polled by the CPU to control SCI operations, or interrupts associated with the flags can be enabled by setting the RX/BK INT ENA (SCICTL2.1) and/or the TX INT ENA (SCICTL2.0) bits active high.

Additional flag and interrupt capability exists for other receiver errors. The RX ERROR flag is the logical OR of the break detect (BRKDT), framing error (FE), receiver overrun (OE), and parity error (PE) bits. RX ERROR high indicates that at least one of these four errors has occurred during transmission. This will also send an interrupt request to the CPU if the RX ERR INT ENA (SCICTL1.6) bit is set.



SCI Registers

SCI Baud Rate Registers

BAUD15(MSB) BAUD14

Baud-Select MSbyte Register (ScixRegs.SCIHBAUD)7 6 5 4 3 2 1 0

BAUD13 BAUD12 BAUD11 BAUD10 BAUD9 BAUD8

BAUD6

Baud-Select LSbyte Register (ScixRegs.SCILBAUD)7 6 5 4 3 2 1 0

BAUD5 BAUD4 BAUD3 BAUD2 BAUD1BAUD7 BAUD0(LSB)

SCI baud rate =

LSPCLK(BRR + 1) x 8

LSPCLK16

, BRR = 1 to 65535

, BRR = 0

Baud Rate Determination: The values in the baud-select registers (SCIHBAUD and SCILBAUD) concatenate to form a 16 bit number that specifies the baud rate for the SCI.

• For BRR = 1 to 65535: SCI Baud Rate = 8)1( ×+BRR

LSPCLK bits/sec

• For BRR = 0: SCI Baud Rate = 16

LSPCLK bits/sec

Max data rate = 6.25 Mbps @ 100 MHz

Note that the CLKOUT for the SCI module is one-half the CPU clock rate.



Select SCI RegistersControl 1 ScixRegs.SCICTL1

Reset, Transmitter / Receiver EnableTX Wake-up, Sleep, RX Error Interrupt Enable

Control 2 ScixRegs.SPICTL2TX Buffer Full / Empty Flag, TX Ready Interrupt EnableRX Break Interrupt Enable

Receiver Status ScixRegs.SCIRXSTError Flag, Ready, Flag Break-Detect Flag, Framing Error Detect Flag, Parity Error Flag, RX Wake-up Detect Flag

FIFO Transmit ScixRegs.SCIFFTX

FIFO Receive ScixRegs.SCIFFRXFIFO Enable, FIFO ResetFIFO Over-flow flag, Over-flow ClearNumber of Words in FIFO (FIFO Status)FIFO Interrupt Enable, Interrupt Status, Interrupt ClearFIFO Interrupt Level (Number of Words in FIFO)

Note: refer to the reference guide for a complete listing of registers

SCI Summary

SCI Summary

Asynchronous communications format65,000+ different programmable baud ratesTwo wake-up multiprocessor modes

Idle-line wake-up & Address-bit wake-upProgrammable data word format

1 to 8 bit data word length1 or 2 stop bitseven/odd/no parity

Error Detection FlagsParity error; Framing error; Overrun error; Break detection

Transmit FIFO and receive FIFOIndividual interrupts for transmit and receive



Local Interconnect Network (LIN) Local Interconnect Network (LIN)

Compliant to the LIN2.0 protocol Specification Package

Module based on SCI (core) with added hardware features for LIN compatibility:

Error detectorMask filterSynchronizerMulti-buffered receiver/transmitter

Standard is based on SCI (UART) serial data link format

Communication concept is single-master/multiple-slave with message identification for multi-cast transmission between any network nodes

Module can be used in LIN mode or SCI (UART) mode

LIN Block Diagram

SCIRXSHF

7 RD0 07 RD1 07 RD2 07 RD3 07 RD4 07 RD5 07 RD6 07 RD7 0

7 TD7 07 TD6 07 TD5 07 TD4 07 TD3 07 TD2 07 TD1 07 TD0 0

SCITXSHF

MaskFilter

Sync

hron

izerLINRX/

SCIRXLINTX/SCITX

ChecksumCalculator

ParityCalculator

BitMonitor



LIN Message Frame and Data Timing

LIN Message Frame

Sync Break – beginning of a messageSync Field – bit rate informationID Field – content of a messageData Field – consists of 1 data byte, 1 start bit, and 1

stop bit (10 bits total)Checksum Field – consists of 1 checksum byte, 1 start

bit and 1 stop bit (10 bits total)In-Frame & Interbyte Spaces – can be 0

SyncBreak

SyncField

IDField

DataField

CheckSumField

DataField

DataField

DataField

DataField

Interbyte SpacesIn-Frame Space

1 to 8 Data Fields

Master Header Response

Message Frame

LIN Data Timing

LIN module is clocked at ½ the CPU clock (SYSCLKOUT)

To make a determination of the bit value, 16 samples of each bit are taken with majority vote on samples 8, 9, and 10

MajorityVote

LINRX

LM_CLK(Internal)

MajorityVote

MajorityVote



LIN Summary

LIN Summary

Functionally compatible with standalone SCI of C28x devicesIdentification masks for filteringAutomatic master header generation228 programmable transmission ratesAutomatic wakeup supportError detection (bit, bus, no response, checksum, synchronization, parity)Multi-buffered receive/transmit units



Inter-Integrated Circuit (I2C) Inter-Integrated Circuit (I2C)

Philips I2C-bus specification compliant, version 2.1Data transfer rate from 10 kbps up to 400 kbpsEach device can be considered as a Master or SlaveMaster initiates data transfer and generates clock signalDevice addressed by Master is considered a SlaveMulti-Master mode supportedStandard Mode – send exactly n data values (specified in register)Repeat Mode – keep sending data values (use software to initiate a stop or new start condition)

28xxI2C

I2CController

I2CEPROM

28xxI2C

. .

. . . . . . . . . .Pull-up

Resisters

VDD

Serial Data (SDA)Serial Clock (SCL)

I2C Block Diagram

TX FIFO

RX FIFO

I2CDXR

I2CDRR

I2CXSR

I2CRSR

ClockCircuits

SDA

SCL



I2C Operating Modes and Data Formats

I2C Operating Modes

Operating Mode Description

Slave-receiver mode Module is a slave and receives data from a master(all slaves begin in this mode)

Slave-transmitter mode Module is a slave and transmits data to a master(can only be entered from slave-receiver mode)

Master-receiver mode Module is a master and receives data from a slave(can only be entered from master-transmit mode)

Master-transmitter mode Module is a master and transmits to a slave(all masters begin in this mode)

I2C Serial Data Formats

S Slave Address R/W ACK Data DataACK ACK P1 7 1 1 n 1 n 1 17-Bit Addressing Format

S 11110AA R/W ACK AAAAAAAA DataACK ACK P1 7 1 1 8 1 n 1 110-Bit Addressing Format

S Data ACK Data DataACK ACK P1 n 1 n 1 n 1 1Free Data Format

R/W = 0 – master writes data to addressed slaveR/W = 1 – master reads data from the slaven = 1 to 8 bitsS = Start (high-to-low transition on SDA while SCL is high)P = Stop (low-to-high transition on SDA while SCL is high)



I2C ArbitrationArbitration procedure invoked if two or more master-transmitters simultaneously start transmission

Procedure uses data presented on serial data bus (SDA) by competing transmittersFirst master-transmitter which drives SDA high is overruled by another master-transmitter that drives SDA lowProcedure gives priority to the data stream with the lowest binary value

1 0

1 0 0 1 0 1

1 0 0 1 0 1

SCL

SDA

Data from device #1

Data from device #2

Device #1 lost arbitration and switches to slave-

receiver mode

Device #2 drives SDA

I2C Summary

I2C Summary

Compliance with Philips I2C-bus specification (version 2.1)7-bit and 10-bit addressing modesConfigurable 1 to 8 bit data wordsData transfer rate from 10 kbps up to 400 kbpsTransmit FIFO and receive FIFO




Controller Area Network (CAN)A Multi-Master Serial Bus System

CAN 2.0B StandardHigh speed (up to 1 Mbps)Add a node without disturbing the bus (number of nodes not limited by protocol)Less wires (lower cost, less maintenance, and more reliable)Redundant error checking (high reliability)No node addressing (message identifiers)Broadcast based signaling

C

ED

AB

CAN does not use physical addresses to address stations. Each message is sent with an identifier that is recognized by the different nodes. The identifier has two functions – it is used for message filtering and for message priority. The identifier determines if a transmitted message will be received by CAN modules and determines the priority of the message when two or more nodes want to transmit at the same time.



CAN Bus and Node

CAN Bus

CANNODE B

CANNODE A

CANNODE C

CAN_H

CAN_L

Two wire differential bus (usually twisted pair)Max. bus length depend on transmission rate

40 meters @ 1 Mbps

120Ω120Ω

The MCU communicates to the CAN Bus using a transceiver. The CAN bus is a twisted pair wire and the transmission rate depends on the bus length. If the bus is less than 40 meters the transmission rate is capable up to 1 Mbit/second.

CAN NodeWired-AND Bus Connection

RXTX

CAN Controller(e.g. TMS320F28035)

CAN Transceiver(e.g. TI SN65HVD23x)

CAN_L

CAN_H

120Ω120Ω



Principles of Operation

Principles of OperationData messages transmitted are identifier based, not address basedContent of message is labeled by an identifier that is unique throughout the network

(e.g. rpm, temperature, position, pressure, etc.)All nodes on network receive the message and each performs an acceptance test on the identifierIf message is relevant, it is processed (received); otherwise it is ignoredUnique identifier also determines the priority of the message

(lower the numerical value of the identifier, the higher the priority)

When two or more nodes attempt to transmit at the same time, a non-destructive arbitration technique guarantees messages are sent in order of priority and no messages are lost

Non-Destructive Bitwise ArbitrationBus arbitration resolved via arbitration with wired-AND bus connections

Dominate state (logic 0, bus is high)Recessive state (logic 1, bus is low)

Node A wins arbitration

CAN Bus

Node A

Node B

Node C

StartBit

Node B loses arbitration

Node C loses arbitration



Message Format and Block Diagram

CAN Message FormatData is transmitted and received using Message Frames8 byte data payload per messageStandard and Extended identifier formats

Standard Frame: 11-bit Identifier (CAN v2.0A)

Extended Frame: 29-bit Identifier (CAN v2.0B)

11-bitIdentifier

RTR

SOF

IDE

r0 DLC 0…8 Bytes Data CRC ACKEOF

ArbitrationField

ControlField Data Field

ControlField

11-bitIdentifier

RTR

SOF

IDE

r0 DLC 0…8 Bytes Data CRC ACKr118-bit

IdentifierSRR

EOF

Arbitration Field Data Field

The MCU CAN module is a full CAN Controller. It contains a message handler for transmission and reception management, and frame storage. The specification is CAN 2.0B Active – that is, the module can send and accept standard (11-bit identifier) and extended frames (29-bit identifier).

eCAN Block Diagram

Memory ManagementUnit

CPU Interface,Receive Control Unit

Timer Management Unit

eCAN Memory(512 bytes)

Register and MessageObject Control

Mailbox RAM(512 bytes)

32 Mailboxes(4 x 32-bit words)

32 32

Receive BufferTransmit BufferControl BufferStatus Buffer

SN65HVD23x3.3-V CAN Transceiver

CAN Bus

32

32

DataAddresseCAN0INT eCAN1INT

A message mailboxIdentifier – MIDControl – MCFData low – MDLData high - MDH



The CAN controller module contains 32 mailboxes for objects of 0 to 8-byte data lengths: • configurable transmit/receive mailboxes • configurable with standard or extended indentifier

The CAN module mailboxes are divided into several parts: • MID – contains the identifier of the mailbox • MCF (Message Control Field) – contains the length of the message (to transmit or

receive) and the RTR bit (Remote Transmission Request – used to send remote frames)

• MDL and MDH – contains the data

The CAN module contains registers which are divided into five groups. These registers are located in data memory from 0x006000 to 0x0061FF. The five register groups are:

• Control & Status Registers

• Local Acceptance Masks

• Message Object Time Stamps

• Message Object Timeout

• Mailboxes

eCAN Summary

eCAN Summary

Fully compliant with CAN standard v2.0BSupports data rates up to 1 MbpsThirty-two mailboxes

Configurable as receive or transmitConfigurable with standard or extended identifierProgrammable receive maskUses 32-bit time stamp on messagesProgrammable interrupt scheme (two levels)Programmable alarm time-out

Programmable wake-up on bus activitySelf-test mode


DSP/BIOS

Introduction This module discusses the basic features of using DSP/BIOS in a system. Scheduling threads, periodic functions, and the use of real-time analysis tools will be demonstrated, in addition to programming the flash with DSP/BIOS.


Introduction to DSP/BIOS

DSP/BIOS Configuration Tool

Scheduling DSP/BIOS threads

Periodic Functions

Real-Time Analysis Tools

C2000 Piccolo Workshop - DSP/BIOS 12 - 1

Module Topics

Module Topics DSP/BIOS..................................................................................................................................................12-1

Module Topics........................................................................................................................................12-2 Introduction to DSP/BIOS .....................................................................................................................12-3 DSP/BIOS Configuration Tool...............................................................................................................12-4 Scheduling DSP/BIOS threads...............................................................................................................12-9 Periodic Functions...............................................................................................................................12-14 Real-Time Analysis Tools.....................................................................................................................12-15 Lab 12: DSP/BIOS...............................................................................................................................12-16

12 - 2 C2000 Piccolo Workshop - DSP/BIOS

Introduction to DSP/BIOS

Introduction to DSP/BIOS What is DSP/BIOS?

A full-featured, scalable real-time kernelSystem configuration toolsPreemptive multi-threading schedulerReal-time analysis tools

Why Use DSP/BIOS?

Helps Manage complex system resourcesno need to develop or maintain a “home-brew” kernelfaster time to market

Efficient debugging of real-time applicationsReal-Time Analysis

Create robust applicationsindustry proven kernel technology

Reduce cost of software maintenancecode reuse and standardized software

Integrated with Code Composer Studio IDErequires no runtime license feesfully supported by TI

Uses minimal Mips and Memory (2-8Kw)scalable – use only what is neededeasily fits in limited memory space



DSP/BIOS Configuration Tool The DSP/BIOS Configuration Tool (often called Config Tool or GUI Tool or GUI) creates and modifies a system file called the Text Configuration File (.tcf). If we talk about using .tcf files, we’re also talking about using the Config Tool.

DSP/BIOS Configuration Tool (file .tcf)

System Setup ToolsHandles memory configuration (builds .cmd file), run-time support libraries, interrupt vectors, system setup and reset, etc.

Real-Time Analysis ToolsAllows application to run uninterrupted while displaying debug data

Real-Time SchedulerPreemptive tread manager kernel configures DSP/BIOS scheduling

Real-Time I/OAllows two way communication between threads or between target and PC host

The GUI (graphical user interface) simplifies system design by: • Automatically including the appropriate runtime support libraries • Automatically handles interrupt vectors and system reset • Handles system memory configuration (builds .cmd file) • When a .tcf file is saved, the Config Tool generates 5 additional files:

Filename.tcf Text Configuration File

Filenamecfg_c.c C code created by Config Tool

Filenamecfg.s28 ASM code created by Config Tool

Filenamecfg.cmd Linker command file

Filenamecfg.h header file for *cfg_c.c

Filenamecfg.h28 header file for *cfg.s28

When you add a .tcf file to your project, CCS automatically adds the C and assembly (.s28) files and the linker command file (.cmd) to the project under the Generated Files folder.



1. Creating a New Memory Region (Using MEM) First, to create a specific memory area, open up the .tcf file, right-click on the Memory Section Manager and select “Insert MEM”. Give this area a unique name and then specify its base and length. Once created, you can place sections into it (shown in the next step).

Memory Section Manager (MEM)Generates the main linker command file for your code project

Create memoriesPlace sections

To create a new memory area:

Right-click on MEM and select insert memoryEnter your choice of a name for the memoryRight-click on the memory, and select Properties

fill in base, length, space



2. Placing Sections – MEM Manager Properties The configuration tool makes it easy to place sections. The predefined compiler sections that were described earlier each have their own drop-down menu to select one of the memory regions you defined (in step 1).

Memory Section Manager Properties

To place a section into a memory area:

Right-click on MEM and select PropertiesSelect the desired tab (e.g. Compiler)Select the memory you would like to link each section to



3. PIE Interrupts – HWI Interrupts The configuration tools is also used to assign the interrupt vectors. The vectors are placed into a section named .hwi_vec. The memory manager (MEM) links this section to the proper location in memory.

Hardware Interrupt Manager (HWI)

Config Tool used to assign interrupt vectorsVectors are placed in the section .hwi_vecUse MEM manager to link .hwi_vec to the proper memory



4. Running the Linker Creating the Linker Command File (via .tcf)

When you have finished creating memory regions and allocating sections into these memory areas (i.e. when you save the .tcf file), the CCS configuration tool creates five files. One of the files is BIOS’s cfg.cmd file — a linker command file.

Files Created by the Configuration Tool

*.tcf

*cfg.s28

*cfg.h28

*cfg_c.c

*cfg.h*cfg.cmd

Config tool generates five different files.cmd file is generated from your MEM settingsVectors put into *cfg_c.c

save to compiler

This file contains two main parts, MEMORY and SECTIONS. (Though, if you open and examine it, it’s not quite as nicely laid out as shown above.)

Running the Linker

The linker’s main purpose is to link together various object files. It combines like-named input sections from the various object files and places each new output section at specific locations in memory. In the process, it resolves (provides actual addresses for) all of the symbols described in your code. The linker can create two outputs, the executable (.out) file and a report which describes the results of linking (.map).

Note: The linker gets run automatically when you BUILD or REBUILD your project.



Scheduling DSP/BIOS threads DSP/BIOS Thread Types

Prio

rity

Use SWI to perform HWI ‘follow-up’ activitySWI's are ‘posted’ by softwareMultiple SWIs at each of 15 priority levels

Use TSK to run different programs concurrently under separate contextsTSK's enabled by posting ‘semaphore’ (a signal)

Runs when no service routines are pending Runs as an infinite loop, like traditional while loopAll BIOS data transfers to host occur here

Used to implement ‘urgent’ part of real-time eventTriggered by hardware interruptHWI priorities fixed in hardware

SWISoftware Interrupts

HWIHardware Interrupts

TSKTasks

IDLBackground

Enabling DSP/BIOS in main()

BIOS will enable global interrupts for youMust delete the endless loop at end of main()

main() returns to BIOS and goes to the IDLE thread, allowing BIOS to schedule events, transfer data to the host, etc.An endless loop in main() will keep BIOS from running

void main(void)

{

//*** Initialization

. . .

//*** Enable global interrupts

// asm(“ CLRC INTM”);

//*** Main Loop

// while(1);

} //end of main()



Using Hardware Interrupts - HWI

Interrupt priority fixed by hardware

interrupt void MyHwi(void){}

The HWI DispatcherFor non-BIOS code, use the interrupt keyword to declare an ISR

tells the compiler to perform context save/restore

For DSP/BIOS code, use the Dispatcher to perform the save/restore

Remove the interrupt keyword from the MyHwi()Check the “Use Dispatcher” box when you configure the interrupt vector in the DSP/BIOS configuration tool

This is necessary if you want to use any DSP/BIOS functionality inside the ISR



Using Software Interrupts - SWI

Make each algorithm an independent software interruptSWI scheduling is handled by DSP/BIOS

HWI function triggered by hardwareSWI function triggered by softwaree.g. a call to SWI_post()

Why use a SWI?No limitation on number of SWIs, and priorities for SWIs are user-definedSWI can be scheduled by hardware or software event(s)Defer processing from HWI to SWI

SWI Properties



Managing SWI Priority

Drag and Drop SWIs to change priorityEqual priority SWIs run in the order that they are posted

Drag and Drop SWIs to change priorityEqual priority SWIs run in the order that they are posted

Priority Based Thread SchedulingHWI 2

HWI 1

SWI 3

SWI 2

SWI 1

MAIN

IDLEint1

rtn

post2 rtn

int2

post3 rtn

post1 rtn

rtn

rtn

User sets the priority...BIOS does the scheduling

(highest)

(lowest)

SWI_post(&swi2);



Using Tasks (TSK)SWI vs. TSK

Similar to hardware interrupt, but triggered by SWI_post()SWIs must run to completionAll SWI's use system stackfaster context switchingsmaller code size

SWI SWI_post

start

end

“must run tocompletion”

SEM_post() readies the TSKwhich pends on an eventTSKs can be terminated by S/WEach TSK has its own stackslower context switchinglarger code size

TSK

start

end

Pause

SEM_post

(blockedstate)

SEM_pend


Periodic Functions

Periodic Functions

period

LED LED LED

Using Periodic Functions - PRD

Periodic functions are a special type of SWI that are triggered by DSP/BIOS

Periodic functions run at a user specified rate:- e.g. LED blink requires 0.5 Hz

Use the CLK Manager to specify the DSP/BIOS CLK rate in microseconds per “tick”

Use the PRD Manager to specify the period (for the function) in ticks

Allows multiple periodic functions with different rates

DSP/BIOSCLK

tick

Creating a Periodic Function

period

func1 func1 func1

DSP/BIOSCLK

tick


Real-Time Analysis Tools

Real-Time Analysis Tools Built-in Real-Time Analysis Tools

Gather data on target (3-10 CPU cycles)Send data during BIOS IDL (100s of cycles)Format data on host (1000s of cycles)Data gathering does NOT stop target CPU

Execution Graph

Shows amount of CPU horsepower being consumed

CPU Load Graph

Software logic analyzerDebug event timingand priority

Built-in Real-Time Analysis Tools

Profile routines w/ohalting the CPU

Statistics View

Send debug msgs to hostDoesn’t halt the DSPDeterministic, low DSPcycle countMore efficient thantraditional printf()

Message LOG

LOG_printf(&trace, “LedSwiCount = %u", LedSwiCount++);


Lab 12: DSP/BIOS

Lab 12: DSP/BIOS Objective

The objective of this lab is to become familiar with DSP/BIOS. In this lab exercise, we will make use of the DSP/BIOS configuration tool, implement a software interrupt (SWI) and periodic function (PRD), program the DSP/BIOS project into the flash, and explore the built-in real-time analysis tools. The DSP/BIOS configuration tool creates a text configuration file (*.tcf) and generates a linker command file (*cfg.cmd). This generated linker command file is functionally equivalent to the linker command file previously used. The memory area of the lab linker command file will be deleted; however, part of the sections area will be used to link sections that are not part of DSP/BIOS. In the lab files we will change the CLA HWI (CLA1_INT1_ISR) to a SWI and replace the LED blink routine with a periodic function. The steps required to properly configure the software for execution from internal flash memory will be covered. Features of the real-time analysis tools, such as the CPU Load Graph, Execution Graph, Message Log, and RTA Control Panel will be demonstrated.

Lab 12: DSP/BIOS

ADCRESULT0

ePWM2

connectorwire

TB CounterCompare

Action Qualifier

ePWM1ADCINA0



...

datamemory

poin

ter

rew

ind

Display using CCS


_Cla1Task8

Objective:Use DSP/BIOS Configuration Tool to:

Handle system memory & interrupt vectorsCreate a .tcf file

Change CLA CLA1_INT1_ISR HWI to SWIReplace LED blink routine with a Periodic FunctionProgram system into Flash Memory

Procedure

Project File 1. A project named Lab12.pjt has been created for this lab. Open the project by

clicking on Project Open… and look in C:\C28x\Labs\Lab12. All Build Options have been configured the same as the previous lab. The files used in this lab are:


Lab 12: DSP/BIOS

Adc.c Filter.cCla_10_12.c Flash.cClaTasks.asm Gpio.cCodeStartBranch.asm Lab_12.cmdDefaultIsr_12.c Main_12.cDelayUs.asm Passwords.asmDSP2803x_GlobalVariableDefs.c PieCtrl_12.cDSP2803x_Headers_BIOS.cmd SysCtrl.cECap_7_8_9_10_12.c Watchdog.cEPwm_7_8_9_10_12.c

Edit Lab.h File 2. Edit Lab.h to uncomment the line that includes the labcfg.h header file. This is the

DSP/BIOS generated include file, and is needed to allow code to access the DSP/BIOS functions and data structures. Next, comment out the line that includes the “DSP2803x_DefaultIsr.h” ISR function prototypes. DSP/BIOS will supply its own ISR function prototypes.

3. In our lab setup, we are running the ADC at a 50 kHz interrupt rate. Such a high frequency interrupt would typically be handled directly in the HWI, as SWIs and TSKs have some overhead associated with them and lauching them this frequently can cause very large processing loads on the CPU. DSP/BIOS is flexible in this way. You can have some interrupts processed directly in the HWI, and others delegated to SWIs or TSKs. For purposes of this lab however, we would like to illustrate how to code a SWI. Therefore, we will convert the ADC ISR into a SWI. To reduce the CPU load, we are going to reduce the frequency of the ADC sample rate by half to 25 kHz.

In Lab.h modify the constant definition for the ADC sample rate as follows:

#define ADC_SAMPLE_PERIOD 2399 // 25 KHz sampling

Save and close the file.

Remove “rts2800_ml.lib” and Inspect Lab_12.cmd 4. The DSP/BIOS configuration tool supplies its own RTS library. Open the Build

Options and select the Linker tab. In the Libraries Category, find the Include Libraries (-l) box and delete: rts2800_ml.lib.

5. Select the Compiler tab. As the project is now configured, we would get a warning at build time stating that the typedef name has already been declared with the same type. This is because it has been defined twice; once in the header files and again in the include file generated by DSP/BIOS. To suppress the warning select Diagnostics Category and find the Suppress Diagnostic <n> (-pds): box. Type in code number 303. Select OK and the Build Options window will close.

6. We will be using the DSP/BIOS configuration tool to create a linker command file. Open and inspect Lab_12.cmd. Notice that the linker command file does not have a memory


Lab 12: DSP/BIOS

area and includes only a limited sections area. These sections are not part of DSP/BIOS and need to be included in a “user” linker command file. Close the inspected file.

Using the DSP/BIOS Configuration Tool 7. The text configuration file (*.tcf) created by the DSP/BIOS configuration tool controls a

wide range of CCS capabilities. The .tcf file will be used to automatically create and perform memory management. Create a new .tcf file for this lab. On the menu bar click:

File New DSP/BIOS Configuration…

A dialog box appears showing a number of available .tcf seed files. The seed files are used to configure many objects specific to the processor and will be invoked as the first item in your own .tcf file. On the C2xxx tab select the ti.platforms.control28035 template and click OK. A configuration window will open.

8. Save the configuration file by selecting:

File Save As…

and name it Lab.tcf in C:\C28x\Labs\Lab12 then click Save. Close the configuration window and select YES to save changes to Lab.tcf.

9. Add the configuration file to the project. Click:

Project Add Files to Project…

Make sure you’re looking in C:\C28x\Labs\Lab12. Change the “files of type” to view All Files (*.*) and select Lab.tcf. Click OPEN to add the file to the project.

10. In the project window left click the plus sign (+) to the left of DSP/BIOS Config. Notice that the Lab.tcf file is listed.

11. Next, add the generated linker command file Labcfg.cmd to the project. After the file has been added you will notice that it is listed under the source files.

Create New Memory Sections Using the TCF File12. Open the Lab.tcf file by double clicking on Lab.tcf. In the configuration window,

left click the plus sign next to System and the plus sign next to MEM. By default, the Memory Section Manager has combined the memory space L1, L2 and L3DPSARAM into a single memory block called DPSARAM. It has also combined M0 and M1SARAM into a single memory block called MSARAM.

13. Next, we will add some of the additional memory sections that will be needed for the lab exercises in this module. To add a memory section:

Right click on MEM – Memory Section Manager and select Insert MEM. Rename the newly added memory section to BEGIN_FLASH. Repeat the process and add the following memory sections: CLAMSGRAM1, CLAMSGRAM2, CSM_RSVD, IQTABLES, L3DPSARAM, and PASSWORDS. Double check and see that all seven memory sections have been added.


Lab 12: DSP/BIOS

14. Modify the base addresses, length, and space of each of the memory sections to correspond to the memory mapping shown in the table below. To modify the length, base address, and space of a memory section, right click on the memory in the configuration tool, and select Properties.

Memory Base Length Space

BEGIN_FLASH 0x3F 7FF6 0x0002 code

CLAMSGRAM1 0x00 1480 0x0080 data

CLAMSGRAM2 0x00 1500 0x0080 data

CSM_RSVD 0x3F 7F80 0x0076 code

IQTABLES 0x3F E000 0x0B50 code

L3DPSARAM 0x00 9000 0x1000 code

PASSWORDS 0x3F 7FF8 0x0008 code

15. Modify the base addresses, length, and space of each of the memory sections to avoid memory conflicts with the newly added memory sections as shown in the table below.

Memory Base Length Space

BOOTROM 0x3F F27C 0x0D44 code

DPSARAM 0x00 8800 0x0800 data

FLASH 0x3E 8000 0xFF80 code

Link Uninitialized Sections to RAM 16. Right click on MEM – Memory Section Manager and select Properties.

Select the Compiler Sections tab and link the following uninitialized sections into the MSARAM memory block via the pull-down boxes.

MSARAM

.bss

.ebss


Lab 12: DSP/BIOS

Link Initialized Sections to Flash All initialized sections must be linked to the on-chip flash memory. Each initialized section has two addresses associated with it. First, it has a LOAD address which is the address to which it gets loaded at load time (or at flash programming time). Second, it has a RUN address which is the address from which the section is accessed at runtime. The linker assigns both addresses to the section. Most initialized sections can have the same LOAD and RUN address in the flash. However, some initialized sections need to be loaded to flash, but then run from RAM. This is required, for example, if the contents of the section needs to be modified at runtime by the code.

17. This step assigns the RUN address of those sections that need to run from flash. Using the MEM – Memory Section Manager in the DSP/BIOS configuration tool link the following sections to on-chip flash memory via the pull-down boxes:

BIOS Data tab BIOS Code tab Compiler Sections tab

.gblinit .bios .text

.sysinit .switch

.hwi .cinit

.rtdx_text .pinit

.econst / .const

.data / .cio

18. This step assigns the LOAD address of those sections that need to load to flash. Again using the MEM – Memory Section Manager in the DSP/BIOS configuration tool select the Load Address tab and check the “Specify Separate Load Addresses” box. Then set all entries to the FLASH memory block.

19. Click the BIOS Data tab and notice that the .stack section has been linked into memory. Click OK to close the window.

20. The section named “IQmath” is an initialized section that needs to load to and run from flash. This section is not linked using the DSP/BIOS configuration tool (because it is neither a standard compiler section nor a DSP/BIOS generated section). Instead, this section is linked with the user linker command file (Lab_12.cmd). Open and inspect Lab_12.cmd. Previously the “IQmath” section was linked to L0SARAM. Notice that this section is now linked to FLASH.


Lab 12: DSP/BIOS

Set the Stack Size in the TCF File Recall in the previous lab exercise that the stack size was set using the CCS project Build Options. When using the DSP/BIOS configuration tool, the stack size is instead specified in the .tcf file. First we need to remove the stack size setting from the project Build Options.

21. Click: Project Build Options… and select the Linker tab. Delete the entry of 0x200 in the Stack Size box. Select OK to close the Build Options window.

22. Using the MEM – Memory Section Manager select the General tab. Set the Stack Size to 0x100. The stack size needs to be reduced from 0x200 to 0x100 because of the limited amount of available RAM on the device when using DSP/BIOS. Click OK to close the window.

Copying .hwi_vec Section from Flash to RAM The DSP/BIOS .hwi_vec section contains the interrupt vectors. This section must be loaded to flash (load address) but run from RAM (run address). The code that performs this copy is located in InitPieCtrl(). The linker command file generated by the DSP/BIOS configuration tool generates global symbols that can be accessed by code in order to determine the load address, run address, and length of the .hwi_vec section. The RTS library contains a memory copy function called memcpy() which will be used to perform the copy.

23. Open and inspect InitPieCtrl() in PieCtrl_12.c. Notice the memcpy() function and the symbols used to initialize (copy) the .hwi_vec section.

Copying the .trcdata Section from Flash to RAM The DSP/BIOS .trcdata section is used by CCS and DSP/BIOS for certain real-time debugging features. This section must be loaded to flash (load address) but run from RAM (run address). The linker command file generated by the DSP/BIOS configuration tool generates global symbols that can be accessed by code in order to determine the load address, run address, and length of the .trcdata section. The memory copy function memcpy() will again be used to perform the copy.

The copying of .trcdata must be performed prior to main(). This is because DSP/BIOS modifies the contents of .trcdata during DSP/BIOS initialization, which also occurs prior to main(). The DSP/BIOS configuration tool provides a user initialization function which will be used to perform the .trcdata section copy prior to both main() and DSP/BIOS initialization.

24. In the DSP/BIOS configuration file (Lab.tcf) and select the Properties for the Global Settings. Check the box “Call User Init Function” and enter the UserInit() function name with a leading underscore: _UserInit. This will cause the function UserInit() to execute prior to main(). Click OK to close the window.

25. Open and inspect the file Main_12.c. Notice that the function UserInit() is used to copy the .trcdata section from its load address to its run address before main().


Lab 12: DSP/BIOS

Initializing the Flash Control Registers The initialization code for the flash control registers cannot execute from the flash memory (since it is changing the flash configuration!). Therefore, the initialization function for the flash control registers must be copied from flash (load address) to RAM (run address) at runtime. The memory copy function memcpy() will again be used to perform the copy. The initialization code for the flash control registers InitFlash() is located in the Flash.c file.

26. Open and inspect Flash.c. The C compiler CODE_SECTION pragma is used to place the InitFlash() function into a linkable section named “secureRamFuncs”.

27. Since the DSP/BIOS configuration tool does not know about user defined sections, the “secureRamFuncs” section will be linked using the user linker command file Lab_12.cmd. Open and inspect Lab_12.cmd. The “secureRamFuncs” will load to flash (load address) but will run from LSARAM (run address). Also notice that the linker has been asked to generate symbols for the load start, load size, and run start addresses.

28. Open and inspect Main_12.c. Notice that the memory copy function memcpy() is being used to copy the section “secureRamFuncs”, which contains the initialization function for the flash control registers. Close all the inspected files.

Setup PIE Vectors for Interrupts in the TCF File Next, we will setup all of the PIE interrupt vectors that will be needed for the lab exercises in this module. This will include all of the vectors used in the previous lab exercises. (Note: the PieVect.c file is not used since DSP/BIOS generates the interrupt vector table).

29. Modify the configuration file Lab.tcf to setup the PIE vector for the watchdog interrupt. Click on the plus sign (+) to the left of Scheduling and again on the plus sign (+) to the left of HWI – Hardware Interrupt Service Routine Manager. Click the plus sign (+) to the left of PIE INTERRUPTS. Locate the interrupt entry for the watchdog at PIE_INT1_8. Right click, select Properties, and type _WAKEINT_ISR (with a leading underscore) in the function field. Click OK to save.

30. Setup the PIE vector for the ADC interrupt. Locate the interrupt entry for the ADC at PIE_INT1_1. Right click, select Properties, and type _ADCINT1_ISR (with a leading underscore) in the function field. Click OK to save.

31. Setup the PIE vector for the ECAP1 interrupt. Locate the interrupt entry for the ECAP1 at PIE_INT4_1. Right click, select Properties, and type _ECAP1_INT_ISR (with a leading underscore) in the function field. Click OK to save.

32. Setup the PIE vector for the CLA Task 1 interrupt. Locate the interrupt entry for the CLA Task 1 at PIE_INT11_1. Right click, select Properties, and type _CLA1_INT1_ISR (with a leading underscore) in the function field. Click OK to save. Close the configuration window and select YES to save changes to Lab.tcf.


Lab 12: DSP/BIOS

Prepare main() for DSP/BIOS 33. Open Main_12.c and delete the inline assembly code from main() that enables global

interrupts. DSP/BIOS will enable global interrupts after main().

34. In Main_12.c, remove the endless while() loop from the end of main(). When using DSP/BIOS, you must return from main(). In all DSP/BIOS programs, the main() function should contain all one-time user-defined initialization functions. DSP/BIOS will then take-over control of the software execution. Save and close the file.

Configuring DSP/BIOS Global Settings 35. Open the configuration file Lab.tcf and click on the plus sign (+) to the left of

System. Right click on Global Settings and select Properties. Confirm that the “DSP Speed in MHz (CLKOUT)” field is set to 60 so that it matches the processor speed. Click OK to save the value and close the configuration window. This value is used by the CLK manager to calculate the register settings for the on-chip timers and provide the proper time-base for executing CLK functions.

Create a SWI 36. Open Main_12.c and notice that at the end of main() two new functions have been

added – Cla1Swi() and LedBlink(). We moved part of the CLA1_INT1_ISR() routine from DefaultIsr_12.c to this space in Main_12.c.

37. Open DefaultIsr_12.c and locate the CLA1_INT1_ISR() routine. The entire contents of the CLA1_INT1_ISR() routine was moved to the Cla1Swi() function in Main_12.c with the following exceptions:

• The instruction used to acknowledge the PIE group interrupt

• The GPIO pin (LED) toggle code

Comment: In almost all appplications, the PIE group acknowledge code is left in the HWI (rather than move it to a SWI). This allows other interrupts to occur on that PIE group even if the SWI has not yet executed. On the other hand, we are leaving the GPIO toggle code in the HWI just as an example. It illustrates that you can post a SWI and also do additional operations in the HWI. DSP/BIOS is extremely flexible!

38. Delete the interrupt key word from the CLA1_INT1_ISR. The interrupt keyword is not used when a HWI is under DSP/BIOS control. A HWI is under DSP/BIOS control when it uses any DSP/BIOS functionality, such as posting a SWI, or calling any DSP/BIOS function or macro.

Post a SWI 39. Still in DefaultIsr_12.c add the following SWI_post to the CLA1_INT1_ISR(),

just after the structure used to acknowledge the PIE group:


Lab 12: DSP/BIOS

SWI_post(&CLA1_swi); // post a SWI

This posts a SWI that will execute the CLA1_swi() code that was moved to the Cla1Swi() function in Main_12.c. In other words, the CLA1 interrupt still executes the same code as before. However, most of that code is now in a posted SWI that DSP/BIOS will execute according to the specified scheduling priorities. Save and close the modified files.

Add the SWI to the TCF File 40. In the configuration file Lab.tcf we need to add and setup the Cla1Swi() SWI. Open

Lab.tcf and click on the plus sign (+) to the left of Scheduling and again on the plus sign (+) to the left of SWI – Software Interrupt Manager.

41. Right click on SWI – Software Interrupt Manager and select Insert SWI. Rename SWI0 to CLA1_swi and click OK. This is just an arbitrary name. We want to differentiate the Cla1Swi() function itself (which is nothing but an ordinary C function) from the DSP/BIOS SWI object which we are calling CLA1_swi.

42. Select the Properties for CLA1_swi and type _Cla1Swi (with a leading underscore) in the function field. Click OK. This tells DSP/BIOS that it should run the function Cla1Swi() when it executes the CLA1_swi SWI.

43. We need to have the PIE for the CLA Task 1 interrupt use the dispatcher. The dispatcher will automatically perform the context save and restore, and allow the DSP/BIOS scheduler to have insight into the ISR. You may recall from an earlier lab that the CLA Task 1 interrupt is located at PIE_INT11_1.

Click on the plus sign (+) to the left of HWI – Hardware Interrupt Service Routine Manager. Click the plus sign (+) to the left of PIE INTERRUPTS. Locate the interrupt entry for the CLA Task 1: PIE_INT11_1. Right click, select Properties, and select the Dispatcher tab. Check the “Use Dispatcher” box and select OK. Close the configuration file and click YES to save changes.

Add a Periodic Function Recall that an instruction was used in the CLA1_INT1_ISR to toggle the LED on the ControlCARD. This instruction has been moved into a periodic function that will toggle the LED at the same rate.

44. Open DefaultIsr_12.c and locate the CLA1_INT1_ISR routine. Notice that the instruction used to toggle the LED was moved to the LedBlink() function in Main_12.c:

GpioDataRegs.GPBTOGGLE.bit.GPIO34 = 1; // Toggle the pin

Also, the code used to implement the interval counter for the LED toggle (i.e., the GPIO32_count++ loop), and the declaration of the GPIO32_count itself from the beginning of CLA1_INT1_ISR() have been deleted. These are no longer needed, as DSP/BIOS will implement the interval counter for us in the periodic function configuration (next step in the lab). Close the inspected files.


Lab 12: DSP/BIOS

45. In the configuration file Lab.tcf we need to add and setup the LedBlink_PRD. Open Lab.tcf and click on the plus sign (+) to the left of Scheduling. Right click on PRD – Periodic Function Manger and select Insert PRD. Rename PRD0 to LedBlink_PRD and click OK.

Select the Properties for LedBlink_PRD and type _LedBlink (with a leading underscore) in the function field. This tells DSP/BIOS to run the LedBlink() function when it executes the LedBlink_PRD periodic function object.

Next, in the period (ticks) field type 500. The default DSP/BIOS system timer increments every 1 millisecond, so what we are doing is telling the DSP/BIOS scheduler to schedule the LedBlink() function to execute every 500 milliseconds. A PRD object is just a special type of SWI which gets scheduled periodically and runs in the context of the SWI level at a specified SWI priority. Click OK. Close the configuration file and click YES to save changes.

DSP/BIOS – Real-time Analysis Tools The DSP/BIOS analysis tools complement the CCS environment by enabling real-time program analysis of a DSP/BIOS application. You can visually monitor an MCU application as it runs with essentially no impact on the application’s real-time performance. In CCS, the DSP/BIOS realt-time analysis (RTA) tools are found on the DSP/BIOS menu. Unlike traditional debugging, which is external to the executing program, DSP/BIOS program analysis requires that the target program be instrumented with analysis code. By using DSP/BIOS APIs and objects, developers automatically instrument the target for capturing and uploading real-time information to CCS using these tools.

46. In the next few steps the Log Event Manager will be setup to record the occurrence of an event in real-time while the program executes. We will be using LOG_printf() to write to a log buffer. The LOG_printf() function is a very efficient means of sending a message from the code to the CCS display. Unlike an ordinary C-language printf(), which can consume several hundred CPU cycles to format the data on the MCU before transmission to the CCS host PC, a LOG_printf() transmits the raw data to the host. The host then formats the data and displays it in CCS. This consumes only 10’s of cycles rather than 100’s of cycles.

In Main_12.c notice the following code at the top of the LedBlink() function just before the instruction used to toggle the LED:

static Uint16 LedSwiCount=0; // used for LOG_printf

/*** Using LOG_printf() to write to a log buffer ***/

LOG_printf(&trace, "LedSwiCount = %u", LedSwiCount++);

Close the file.

47. In the configuration file Lab.tcf we need to add and setup the trace buffer. Open Lab.tcf and click on the plus sign (+) to the left of Instrumentation and again on the plus sign (+) to the left of LOG – Event Log Manager.


Lab 12: DSP/BIOS

48. Right click on LOG – Event Log Manager and select Insert LOG. Rename LOG0 to trace and click OK.

49. Select the Properties for trace and confirm that the logtype is set to circular and the datatype is set to printf. Click OK. Close the configuration file and click YES to save changes.

Build – Lab.out 50. At this point we need to build the project, but not have CCS automatically load it since

CCS cannot load code into the flash (the flash must be programmed)! On the menu bar click: Option Customize… and select the “Program/Project CIO” tab and confirm that the “Load Program After Build” is unchecked.

Next select the “Debug Properties” tab and confirm that the “Step over functions without debug information when source stepping” is unchecked. Then click OK.

51. Click the “Build” button to generate Lab.out.

CCS Flash Plug-in 52. Open the Flash Plug-in tool by clicking:

Tools F28xx On-Chip Flash Programmer

53. A Clock Configuration window may open. If needed, in the Clock Configuration window set “OSCCLK (MHz):” to 10, “DIVSEL:” to /2, and “PLLCR Value:” to 12. Then click OK. In the next Flash Programmer Settings window confirm that the selected DSP device to program is F28035 and all options have been checked. Click OK.

54. The CCS Flash Programmer uses the Piccolo™ 10 MHz internal oscillator as the device clock during programming. Confirm the “Clock Configuration” in the upper left corner has the OSCCLK set to 10 MHz, the DIVSEL set to /2, and the PLLCR value set to 12. Recall that the PLL is divided by two, which gives a SYSCLKOUT of 60 MHz.

55. Confirm that all boxes are checked in the “Erase Sector Selection” area of the plug-in window. We want to erase all the flash sectors.

56. We will not be using the plug-in to program the “Code Security Password”. Do not modify the Code Security Password fields. They should remain as all 0xFFFF.

57. In the “Operation” block, notice that the “COFF file to Program/Verify” field automatically defaults to the current .out file. Check to be sure that “Erase, Program, Verify” is selected. We will be using the default wait states, as shown on the slide in this module. The selection for wait-states only affects the verify step, and makes little noticeable difference even if you reduce the wait-states.


Lab 12: DSP/BIOS

58. Click “Execute Operation” to program the flash memory. Watch the programming status update in the plug-in window.

59. After successfully programming the flash memory, close the programmer window.

Running the Code – Using CCS 60. In order to effectively debug with CCS, we need to load the symbolic debug information

(e.g., symbol and label addresses, source file links, etc.) so that CCS knows where everything is in your code. Click:

File Load Symbols Load Symbols Only…

and select Lab12.out in the Debug folder.

61. Reset the CPU. The program counter should now be at 0x3FF8A1, which is the start of the bootloader in the Boot ROM.

62. Under GEL on the menu bar click: EMU Boot Mode Select EMU_BOOT_FLASH. This has the debugger load values into EMU_KEY and EMU_BMODE so that the bootloader will jump to "FLASH" at 0x3F7FF6.

63. Single-Step <F11> through the bootloader code until you arrive at the beginning of the codestart section in the CodeStartBranch.asm file. (Be patient, it will take about 125 single-steps). Notice that we have placed some code in CodeStartBranch.asm to give an option to first disable the watchdog, if selected.

64. Step a few more times until you reach the start of the C-compiler initialization routine at the symbol _c_int00.

65. Now do Debug Go Main. The code should stop at the beginning of your main() routine. If you got to that point succesfully, it confirms that the flash has been programmed properly, that the bootloader is properly configured for jump to flash mode, and that the codestart section has been linked to the proper address.

66. You can now RUN the CPU, and you should observe the LED on the ControlCARD blinking. Try resetting the CPU, select the EMU_BOOT_FLASH boot mode, and then hitting RUN (without doing all the stepping and the Go Main procedure). The LED should be blinking again.

Run the Code – Real-time Analysis Tools It will be interesting to investigate the CPU computational burden of the the different pieces of DSP/BIOS real-time analysis tools that we will be using in this lab exercise. The ‘CPU Load Graph’ feature of DSP/BIOS will provide a quick and easy method for doing this. We will be tabulating these results in the table that follows at various steps throughout the remainder of this lab.


Lab 12: DSP/BIOS

Table 12-1: CPU Computational Burden Results

Case #

Description CPU Load %

1 CLA processing handled in SWI. LED blink handled in PRD. RTA Global Host Enable disabled.

2 Case #1 + LOG_printf in SWI.

3 Case #2 + RTA SWI Logging enabled.

4 Case #3 + RTA SWI Accumulators enabled.

67. Open the RTA Control Panel by clicking DSP/BIOS RTA Control Panel. Uncheck ALL of the boxes. This disables most of the realtime analysis tools. We will selectively enable them in the lab.

68. Open the CPU Load Graph by clicking DSP/BIOS CPU Load Graph. The CPU load graph displays the percentage of available CPU computing horsepower that the application is consuming. The CPU may be running ISRs, software interrupts, periodic functions, performing I/O with the host, or running any user routine. When the CPU is not executing user code, it will be idle (in the DSP/BIOS idle thread).

69. Record the value shown in the CPU Load Graph under “Case #1” in Table 12-1.

70. Open the Message Log. On the menu bar, click:

DSP/BIOS Message Log

The message log dialog box is displaying the commanded LOG_printf() output, i.e. the number of times (count value) that the LedSwi() has executed.

71. Verify that all the check boxes in the RTA Control Panel window are still unchecked. Then, check the box marked “Global Host Enable.” This is the main control switch for most of the RTA tools. We will be selectively enabling the rest of the check boxes in this portion of the exercise.


73. Open the Execution Graph. On the menu bar, click:

DSP/BIOS Execution Graph


Lab 12: DSP/BIOS

Presently, the execution graph is not displaying anything. This is because we have it disabled in the RTA Control Panel.

In the RTA Control Panel, check the top four boxes to enable logging of all event types to the execution graph. Notice that the Execution Graph is now displaying information about the execution threads being taken by your software. This graph is not based on time, but the activity of events (i.e. when an event happens, such as a SWI or periodic function begins execution). Notice that the execution graph simply records DSP/BIOS CLK events along with other system events (the DSP/BIOS clock periodically triggers the DSP/BIOS scheduler). As a result, the time scale on the execution graph is not linear.

The logging of events to the execution graph consumes CPU cycles, which is why the CPU Load Graph jumped as you enabled logging.


75. Open the Statistics View window. On the menu bar, click:

DSP/BIOS Statistics View

Presently, the statistics view window is not changing with the exception of the statistics for the IDL_busyObj row (i.e., the idle loop). This is because we have it disabled in the RTA Control Panel.

In the RTA Control Panel, check the next five boxes (i.e., those with the word “Accumulator” in their description) to enable logging of statistics to the statistics view window. The logging of statistics consumes CPU cycles, which is why the CPU Load Graph jumped as you enabled logging.


77. Table 12-1 should now be completely filled in. Think about the results.

Note: In this lab exercise only the basic features of DSP/BIOS and the real-time analysis tools have been used. For more information and details, please refer to the DSP/BIOS user’s manuals and other DSP/BIOS related training.

Running the Code – Stand-alone Operation (No Emulator) 78. Close Code Composer Studio.

79. Disconnect the USB cable (emulator) from the Docking Station (i.e. remove power from the ControlCARD).

80. Re-connect the USB cable to the Docking Station to power the ControlCARD. The LED should be blinking, showing that the code is now running from flash memory.

End of Exercise


Lab 12: DSP/BIOS

Lab 12 Reference: Programming the Flash

Flash Memory Section Blocks

PASSWORDSlen = 0x8

space = code

BEGIN_FLASHlen = 0x2

space = code

CSM_RSVDlen = 0x76

space = code

FLASHlen = 0xFF80space = code

0x3E 8000

0x3F 7F80

0x3F 7FF6

0x3F 7FF8

base =

SECTIONS{

codestart :> BEGIN_FLASH, PAGE = 0passwords :> PASSWORDS, PAGE = 0csm_rsvd :> CSM_RSVD, PAGE = 0

}

Lab_12.cmd

BIOS Startup Sequence from Flash Memory

0x3F 7FF6

0x3E 8000

0x3F E000

0x3F FFC0

Boot ROM (8Kw)

BROM vector (32w)0x3F F8A1

Boot Code

RESET

0x3F F8A1{SCAN GPIO}

FLASH (64Kw)

Passwords (8w)_c_int00

LB

BIOS code Sections

“rts2800_ml.lib”

“user” code sections

_c_int00 BIOS_reset( )BIOS_init( )main ( )BIOS_start( )

IDL_run( )

main ( ){

……return;

}2

3

4

5

6

7

1


Lab 12: DSP/BIOS

Table 12-2: CPU Computational Burden Results (Solution)

Case #

Description CPU Load %

1 CLA processing handled in SWI. LED blink handled in PRD. RTA Global Host Enable disabled.

27.5

2 Case #1 + LOG_printf in SWI. 27.5

3 Case #2 + RTA SWI Logging enabled. 37.0

4 Case #3 + RTA SWI Accumulators enabled. 48.6


Lab 12: DSP/BIOS


Development Support

Introduction This module contains various references to support the development process.


TI Workshops Download Site

Signal Processing Libraries

TI Development Tools

Additional ResourcesInternet

Product Information Center

C2000 Piccolo Workshop - Development Support 13 - 1

Module Topics

Module Topics Development Support ..............................................................................................................................13-1

Module Topics........................................................................................................................................13-2 TI Support Resources.............................................................................................................................13-3

C28x Signal Processing Libraries......................................................................................................13-3 Experimenter’s Kits...........................................................................................................................13-4 F28335 Peripheral Explorer Kit.........................................................................................................13-5 C2000 ControlCARD Application Kits.............................................................................................13-5 Product Information Resources .........................................................................................................13-6

13 - 2 C2000 Piccolo Workshop - Development Support

TI Support Resources

TI Support Resources TI Workshops Download Site

http://www.tiworkshop.com/survey/downloadsort.asp

Login Name: c28xmdwPassword: ttoc28

C28x Signal Processing Libraries

C2000 Signal Processing LibrariesSignal Processing Libraries & Applications Software Literature #ACI3-1: Control with Constant V/Hz SPRC194ACI3-3: Sensored Indirect Flux Vector Control SPRC207ACI3-3: Sensored Indirect Flux Vector Control (simulation) SPRC208ACI3-4: Sensorless Direct Flux Vector Control SPRC195ACI3-4: Sensorless Direct Flux Vector Control (simulation) SPRC209PMSM3-1: Sensored Field Oriented Control using QEP SPRC210PMSM3-2: Sensorless Field Oriented Control SPRC197PMSM3-3: Sensored Field Oriented Control using Resolver SPRC211PMSM3-4: Sensored Position Control using QEP SPRC212BLDC3-1: Sensored Trapezoidal Control using Hall Sensors SPRC213BLDC3-2: Sensorless Trapezoidal Drive SPRC196DCMOTOR: Speed & Position Control using QEP without Index SPRC214Digital Motor Control Library (F/C280x) SPRC215Communications Driver Library SPRC183DSP Fast Fourier Transform (FFT) Library SPRC081DSP Filter Library SPRC082DSP Fixed-Point Math Library SPRC085DSP IQ Math Library SPRC087DSP Signal Generator Library SPRC083DSP Software Test Bench (STB) Library SPRC084C28x FPU Fast RTS Library SPRC664DSP2803x C/C++ Header Files and Peripheral Examples SPRC892

Available from TI Website ⇒ http://www.ti.com/c2000



Experimenter’s Kits

C2000 Experimenter’s KitsF28027, F28035, F2808, F28335

Experimenter Kits includeF28027, F28035, F2808 or F28335 ControlCARDUSB docking stationC2000 Applications Software CD with example code and full hardware detailsCode Composer Studio v3.3 with code size limit of 32KB

Docking station featuresAccess to ControlCARD signalsBreadboard areasOnboard USB JTAG Emulation

JTAG emulator not required

Available through TI authorized distributors and the TI eStore

TMDXDOCK28027

TMDXDOCK28035

TMDSDOCK2808

TMDSDOCK28335

C2834x Experimenter’s KitsC28343, C28346

Experimenter Kits includeC2834x ControlCARDDocking stationC2000 Applications Software CD with example code and full hardware detailsCode Composer Studio v3.3 with code size limit of 32KB5V power supply

Docking station featuresAccess to ControlCARD signalsBreadboard areasJTAG emulator required – sold separately

Available through TI authorized distributors and the TI eStore

TMDXDOCK28343

TMDXDOCK28346-168



F28335 Peripheral Explorer Kit

F28335 Peripheral Explorer KitExperimenter Kit includes

F28335 ControlCARDPeripheral Explorer baseboardC2000 Applications Software CD with example code and full hardware detailsCode Composer Studio v3.3 with code size limit of 32KB5V DC power supply

Peripheral Explorer featuresADC input variable resistorsGPIO hex encoder & push buttonseCAP infrared sensorGPIO LEDs, I2C & CAN connectionAnalog I/O (AIC+McBSP)

JTAG emulator required – sold separatelyAvailable through TI authorized distributors and the TI eStoreTMDSPREX28335

C2000 ControlCARD Application Kits

C2000 ControlCARD Application KitsDigital Power

Experimenter’s Kit

Digital Power Developer’s

Kit

Resonant DC/DC

Developer’s Kit

Renewable Energy

Developer’s Kit

AC/DC Developer’s

Kit

Kits includesControlCARD and application specific baseboardFull version of Code Composer Studio v3.3 with 32KB code size limit

Software download includes Complete schematics, BOM, gerberfiles, and source code for board and all softwareQuickstart demonstration GUI for quick and easy access to all board featuresFully documented software specific to each kit and application

See www.ti.com/c2000 for more detailsAvailable through TI authorized distributors and the TI eStore

Dual Motor Control and

PFC Developer’s

Kit



Product Information Resources

For More Information . . .

Phone: 800-477-8924 or 972-644-5580Email: [email protected]

Information and support for all TI Semiconductor products/toolsSubmit suggestions and errata for tools, silicon and documents

USA - Product Information Center (PIC)

Website: http://www.ti.com

FAQ: http://www-k.ext.ti.com/sc/technical_support/knowledgebase.htm Device information my.ti.comApplication notes News and eventsTechnical documentation Training

Enroll in Technical Training: http://www.ti.com/sc/training

Internet

Web: http://www-k.ext.ti.com/sc/technical_support/pic/euro.htm

Phone: Language NumberBelgium (English) +32 (0) 27 45 55 32France +33 (0) 1 30 70 11 64Germany +49 (0) 8161 80 33 11Israel (English) 1800 949 0107 (free phone)Italy 800 79 11 37 (free phone)Netherlands (English) +31 (0) 546 87 95 45Spain +34 902 35 40 28Sweden (English) +46 (0) 8587 555 22United Kingdom +44 (0) 1604 66 33 99Finland (English) +358(0) 9 25 17 39 48

Fax: All Languages +49 (0) 8161 80 2045

Email: [email protected]

Literature, Sample Requests and Analog EVM OrderingInformation, Technical and Design support for all Catalog TISemiconductor products/toolsSubmit suggestions and errata for tools, silicon and documents

European Product Information Center (EPIC)


Appendix A – Experimenter’s Kit

C2000 Piccolo Workshop - Appendix A -Experimenter's Kit A - 1

Module Topics

Module Topics Appendix A – Experimenter’s Kit ...........................................................................................................A-1

Module Topics......................................................................................................................................... A-2 F28035 ControlCARD ............................................................................................................................ A-3

F28035 PCB Outline (Top View).......................................................................................................A-3 LD1 / LD2 / LD3................................................................................................................................A-3 SW1....................................................................................................................................................A-3 SW2....................................................................................................................................................A-4 SW3....................................................................................................................................................A-4

F28335 ControlCARD ............................................................................................................................ A-5 F28335 PCB Outline (Top View).......................................................................................................A-5 LD1 / LD2 / LD3................................................................................................................................A-5

Docking Station....................................................................................................................................... A-6 SW1 / LD1..........................................................................................................................................A-6 JP1 / JP2 .............................................................................................................................................A-6 J1 / J2 /J3 / J8 / J9...............................................................................................................................A-6 F2833x Boot Mode Selection .............................................................................................................A-7 F280xx Boot Mode Selection .............................................................................................................A-7 J3 – DB-9 to 4-Pin Header Cable .......................................................................................................A-8

A - 2 C2000 Piccolo Workshop - Appendix A -Experimenter's Kit

F28035 ControlCARD

F28035 ControlCARD

F28035 PCB Outline (Top View)

SW1

SW3 SW2

LD2 LD3LD1

LD1 / LD2 / LD3

SW1


F28035 ControlCARD

SW2

SW3


F28335 ControlCARD

F28335 ControlCARD

F28335 PCB Outline (Top View)

LD2 LD1LD3

LD1 / LD2 / LD3


Docking Station

Docking Station

SW1

JP1

JP2

LD1J1

J2

J3

2833xBoot

280xxBoot

J8J9

SW1 / LD1 SW1 – USB: Power from USB; ON – Power from JP1

LD1 – Power-On indicator

JP1 / JP2 JP1 – 5.0 V power supply input

JP2 – USB JTAG emulation port

J1 / J2 /J3 / J8 / J9 J1 – ControlCARD 100-pin DIMM socket

J2 – JTAG header connector

J3 – UART communications header connector

J8 – Internal emulation enable/disable jumper (NO jumper for internal emulation)

J9 – User virtual COM port to C2000 device (Note: ControlCARD would need to be modified to disconnect the C2000 UART connection from header J3)


Docking Station

Note: The internal emulation logic on the Docking Station routes through the FT2232 USB device. By default this device enables the USB connection to perform JTAG communication and in parallel create a virtual serial port (SCI/UART). As shipped, the C2000 device is not connected to the virtual COM port and is instead connected to J3.

F2833x Boot Mode Selection

F280xx Boot Mode Selection


Docking Station

J3 – DB-9 to 4-Pin Header Cable

Note: This cable is NOT included with the Experimenter’s Kit and is only shown for reference.

Pin-Out Table for Both Ends of the Cable:

DB-9 female SIL 0.1" femalePin# Pin#--------------------------------------------------------------2 (black) 1 (TX)3 (red) 4 (RX)5 (bare wire) 3 (GND)

Note: pin 2 on SIL is a no-connect

DB-9 Male


Appendix B – Addressing Modes

Introduction Appendix B will describe the data addressing modes on the C28x. Immediate addressing allows for constant expressions which are especially useful in the initialization process. Indirect addressing uses auxiliary registers as pointers for accessing organized data in arrays. Direct addressing is used to access general purpose memory. Techniques for managing data pages, relevant to direct addressing will be covered as well. Finally, register addressing allows for interchange between CPU registers.

Learning Objectives

Learning Objectives

Explain .sect and .usect assembly directives

Explain assembly addressing modes

Understand instruction formats

Describe options for each addressing mode

C2000 Piccolo Workshop - Appendix B - Addressing Modes B - 1

Module Topics

Module Topics Appendix B – Addressing Modes .............................................................................................................B-1

Module Topics......................................................................................................................................... B-2 Labels, Mnemonics and Assembly Directives ......................................................................................... B-3 Addressing Modes................................................................................................................................... B-4 Instruction Formats ................................................................................................................................ B-5 Register Addressing ................................................................................................................................ B-6 Immediate Addressing............................................................................................................................. B-7 Direct Addressing ................................................................................................................................... B-8 Indirect Addressing............................................................................................................................... B-10 Review................................................................................................................................................... B-13

Exercise B.........................................................................................................................................B-14 Lab B: Addressing................................................................................................................................. B-15 OPTIONAL Lab B-C: Array Initialization in C .................................................................................... B-17 Solutions................................................................................................................................................ B-18

B - 2 C2000 Piccolo Workshop - Appendix B - Addressing Modes

Labels, Mnemonics and Assembly Directives

Labels, Mnemonics and Assembly Directives

.def startcount .set 9

;create an array x of 10 wordsx .usect “mydata”, 10

.sect “code”start: C28OBJ ;operate in C28x mode

MOV ACC,#1next: MOVL XAR1,#x

MOV AR2,#countloop: MOV *XAR1++,AL

BANZ loop,AR2--bump: ADD ACC,#1

SB next,UNC

.ref start

.sect “vectors”;make reset vector address 'start'

reset: .long start

Labels and Mnemonics

MnemonicsLines of instructionsUse upper or lower caseBecome components of program memory

LabelsOptional for all assembly instructions and most assembler directivesMust begin in column 1The “ : ” is not treated as part of the label nameUsed as pointers to memory or instructions

.def startcount .set 9

; create an array x of 10 wordsx .usect “mydata”, 10

.sect “code”start: C28OBJ ;operate in C28x mode

MOV ACC,#1next: MOVL XAR1,#x

MOV AR2,#countloop: MOV *XAR1++,AL

BANZ loop,AR2--bump: ADD ACC,#1

SB next,UNC

Assembly Directives.ref start.sect “vectors”;make reset vector address 'start'

reset: .long start

Directives allow you to:Define a label as globalReserve space in memory for un-initialized variablesInitialized memory

Begin with a period (.) and are lower case

Used by the linker to locate code and data into specified sections

initialized section.sect “name”

used for code or constants

uninitialized sectionlabel .usect “name”,5

used for variables

Directives


Addressing Modes

Addressing Modes Addressing Modes

Mode Symbol Purpose

Register Operate between Registers

Immediate # Constants and Initialization

Direct @ General-purpose access to data

Indirect * Support for pointers – access arrays,lists, tables

(register)

(constant)

(paged)

(pointer)

Four main categories of addressing modes are available on the C28x. Register addressing mode allows interchange between all CPU registers, convenient for solving intricate equations. Immediate addressing is helpful for expressing constants easily. Direct addressing mode allows information in memory to be accessed. Indirect addressing allows pointer support via dedicated ‘auxiliary registers’, and includes the ability to index, or increment through a structure. The C28x supports a true software stack, desirable for supporting the needs of the C language and other structured programming environments, and presents a stack-relative addressing mode for efficiently accessing elements from the stack. Paged direct addressing offers general-purpose single cycle memory access, but restricts the user to working in any single desired block of memory at one time.


Instruction Formats

Instruction Formats

Instruction Formats

What is a “REG”? 16-bit Access = AR0 through AR7, AH, AL, PH, PL, T and SP32-bit Access = XAR0 through XAR7, ACC, P, XT

What is an “#imm”?an immediate constant stored in the instruction

What is a “mem”?A directly or indirectly addressed operand from data memory Or, one of the registers from “REG”! loc16 or loc32 (for 16-bit or 32-bit data access)

INSTR REG NEG ALINSTR REG,#imm MOV ACC,#1INSTR REG,mem ADD AL,@xINSTR mem,REG SUB AL,@AR0 INSTR mem,#imm MOV *XAR0++,#25

INSTR dst ,src Example

The C28x follows a convention that uses instruction, destination, then source operand order (INSTR dst, src). Several general formats exist to allow modification of memory or registers based on constants, memory, or register inputs. Different modes are identifiable by their leading characters (# for immediate, * for indirect, and @ for direct). Note that registers or data memory can be selected as a ‘mem’ value.


Register Addressing

Register Addressing Register Addressing

Allows for efficient register to register operation16-bit and 32-bit Register Address modesReduces code overhead, memory accesses, and memory overhead

AR0 – AR7 AH AL PH PL T TL DP SP16-bit Registers

XAR0 – XAR7 ACC P XT32-bit Registers

Register addressing allows the exchange of values between registers, and with certain instructions can be used in conjunction with other addressing modes, yielding a more efficient instruction set. Remember that any ‘mem’ field allows the use of a register as the operand, and that no special character (such as @, *, or #) need be used to specify the register mode.

Register Addressing – Example

MOVL loc32,ACC

MOVL @XT,ACC

MOV loc16,Ax,COND

MOV @AR1,AL,GT

MOV Ax,loc16

MOV AH,@AL

User Guide & Dis-assembler use @ for second register

Format

Instruction

Format

Instruction


Immediate Addressing

Immediate Addressing Immediate Addressing – “#”

Fixed value part of program memory instructionSupports short (8-bit) and long (16-bit) immediate constantsLong immediate can include a shiftUsed to initialize registers, and operate with constants

OPCODE 8-bit OPERANDone word instruction

OPCODE16-bit OPERAND

two word instruction

Immediate addressing allows the user to specify a constant within an instruction mnemonic. Short immediate are single word, and execute in a single cycle. Long (16-bit) immediate allow full sized values, which become two-word instructions - yet execute in a single instruction cycle.

Immediate Addressing – Example

Long Immediate, 2 Words (AND)

loc16#16Bit

AND

AND loc16,#16Bit

Ax

#16Bit

loc16AND

AND Ax,loc16,#16Bit

ACC

#16Bit

shiftAND

AND ACC,#16Bit,<<0-16

Short Immediate, 1 Word (ANDB)

AND automatically replaced byANDB if IMM value is 8 bits or less

ANDB

ANDB Ax,#8Bit

Ax #8Bit


Direct Addressing

Direct Addressing Direct addressing allows for access to the full 4-Meg words space in 64 word “page” groups. As such, a 16-bit Data Page register is used to extend the 6-bit local address in the instruction word. Programmers should note that poor DP management is a key source of programming errors. Paged direct addressing is fast and reliable if the above considerations are followed. The watch operation, recommended for use whenever debugging, extracts the data page and displays it as the base address currently in use for direct addressing.

Direct Addressing – “@”

Data memory space divided into 65,536 pages with 64 words on each pageData page pointer (DP) used to select active page16-bit DP is concatenated with a 6-bit offset from the instruction to generate an absolute 22-bit addressAccess data on a given page in any order

00 0000 0000 0000 00 00 0000• • • Page 0: 00 0000 – 00 003F

00 0000 0000 0000 00 11 111100 0000 0000 0000 01 00 0000

• • • Page 1: 00 0040 – 00 007F00 0000 0000 0000 01 11 111100 0000 0000 0000 10 00 0000

• • • Page 2: 00 0080 – 00 00BF00 0000 0000 0000 10 11 1111

• • • • •• • • • •

11 1111 1111 1111 11 00 0000• • • Page 65,535: 3F FFC0 – 3F FFFF

11 1111 1111 1111 11 11 1111

OffsetData Page Data Memory


Direct Addressing

Direct Addressing – Example

Z = X + Y

x .usect “samp”,3.sect “code”

MOV AL,@xMOVW DP,#x

ADD AL,@yMOV @z, AL

Data Memoryaddress data0001C0 0001 … …

x: 0001FD 1000y: 0001FE 0500z: 0001FF

64Page7[00]...

Page7[3D]Page7[3E]Page7[3F] 1500

variations:MOVW DP,#imm ;2W, 16-bit (4 Meg)

MOVZ DP,#imm ;1W, 10-bit (64K)MOV DP,#imm ;DP(15:10) unchanged

0000 0000 0000 0001 1111 11110 0 0 1 F F

DP offset

0 0 0 0 1 5 0 00 0 0 0 1 0 0 0

AccumulatorDP=0007- - - - - - - -

MOV AL,@xADD AL,@y

MOV @z,AL

Direct Addressing – CaveatsZ = X + Y

x .usect “samp”,3.sect “code”

ADD AL,@yMOV @z, AL

Data Memoryaddress data0001C0 0001 … …

x: 0001FF 1000y: 000200 0500

… …

Page7[00]...

Page7[3F]

Page8[00]

MOVW DP,#x0 0 0 0 1 0 0 10 0 0 70 0 0 0 1 0 0 00 0 0 7

AccumulatorDP=0007- - - - - - - -0 0 0 7

MOV AL,@x

0000 0000 0000 0001 1111 1111DP offset

0000 0000 0000 0010 0000 0000

expecting 1500

Solution: Group and block variables in ASM file:x .usect “samp”,3,1 ;Force all locations to same datay .set x+1 ;page (1st hole, else linker error)z .set x+2 ;Assign vars within block

(X and Y not on the same page)


Indirect Addressing

Indirect Addressing

Indirect Addressing – “*”

Auxiliary Registers (XARn) used to access full data memory spaceAddress Register Arithmetic Unit (ARAU) used to modify the XARnAccess data from arrays anywhere in data memory in an orderly fashion

Data MemoryXAR0XAR1XAR2XAR3XAR4XAR5XAR6XAR7

ARAU

Any of eight hardware pointers (ARs) may be employed to access values from the first 64K of data memory. Auto-increment or decrement is supported at no additional cycle cost. XAR register formats offer larger 32-bit widths, allowing them to access across the full 4-Giga words data space.

Indirect Addressing Modes

Auto-increment / decrement: *XARn++, *--XARnPost-increment or Pre-decrement

Offset: *+XARn[AR0 or AR1], *+XARn[3bit]Offset by 16-bit AR0 or AR1, or 3-bit constant

Stack Relative: *-SP[6bit]Index by 6-bit offset (optimal for C)

Immediate Direct: *(0:16bit)Access low 64K

Circular: *AR6%++AR1(7:0) is buffer sizeXAR6 is current address


Indirect Addressing

Indirect Addressing – ExampleAutoincrement

∑=

=4

0nnxy

Data

x0x1x2x3x4

x

y

XAR2

*(0:16bit) - 16 bit label - must be in lower 64K- 2 word instruction

x .usect “samp”,6y .set (x + 5)

.sect “code”MOVL XAR2,#xMOV ACC,*XAR2++ADD ACC,*XAR2++ADD ACC,*XAR2++ADD ACC,*XAR2++ADD ACC,*XAR2++MOV *(0:y),AL

Fast, efficient access to arrays, lists, tables, etc.

Indexed addressing offers the ability to select operands from within an array without modification to the base pointer. Stack-based operations are handled with a 16-bit Stack Pointer register, which operates over the base 64K of data memory. It offers 6-bit non-destructive indexing to access larger stack-based arrays efficiently.

Indirect Addressing – ExampleOffset

x[2] = x[1] + x[3]

MOVL XAR2,#xMOV AR0,#1MOV AR1,#3 MOV ACC,*+XAR2[AR0]ADD ACC,*+XAR2[AR1]MOV *+XAR2[2],AL

x .usect “.samp”,5.sect “.code”

MOVL XAR2,#xMOV ACC,*+XAR2[1]ADD ACC,*+XAR2[3]MOV *+XAR2[2],AL

x .usect “.samp”,5.sect “.code”

x

Data

x0x1x2x3x4

XAR2[3]

3 bit offset16 bit offsetAllows offset into arrays with fixed base pointer


Indirect Addressing

Indirect Addressing – ExampleStack Relative

.sect “.code”

x2 = x1 + x3

MOV *-SP[2],AL

ADD AL,*-SP[3]

MOV AL,*-SP[1]Accumulator

0 0 0 0 0 2 0 0

0 0 0 0 0 3 2 0

0 1 2 00 0 5 00 2 0 0emptyempty

Data Memory

- SP -

x2x1

x3? ? ? ?0 3 2 0

Instr. 1

Instr. 2

Instr. 3

Useful for stack based operations

Indirect Addressing – ExampleCircular

(AR1 Low is set to buffer size – 1)

AR1 Low (16)end of buffer ---- ----

start of buffer

(align on 256 word boundary)

AAAA AAAAAAAA … AAAA

SECTIONS{ Buf_Mem: align(256) { } > RAM PAGE 1

. . . }

LINKER.CMD

circularbufferrange

Element 0

Element N-1

Buffer Size N

XAR6 (32)access pointerAAAA AAAAAAAA … AAAA xxxx xxxx

N-1

0000 0000

MAC P,*AR6%++,*XAR7++


Review

Review Addressing Range Review

0x000000

0x00003F

0x00FFFF

0xFFFFFFFF

Stack Addressing

SP64K Indirect

Addressing XARn

4G

0x3FFFFF

Direct Addressing

DP(16+6)4M

Data memory can be accessed in numerous ways:

• Stack Addressing: allows a range to 64K • Direct Addressing: Offers a 16-bit DP plus a 6-bit offset, allowing a 4M range • Indirect Addressing: Offers the full 4G range


Review

Exercise B

Exercise B: AddressingGiven: DP = 4000 DP = 4004 DP = 4006 Address/Data (hex) 100030 0025 100100 0105 100180 0100Fill in the 100031 0120 100101 0060 100181 0030table below 100032 100102 0020 100182 0040

Src Mode Program ACC DP AR1 AR2MOVW DP,#4000hMOVL XAR1,#100100hMOVL XAR2,#100180hMOV AL,@31hADD AL,*XAR1++SUB AL,@30hADD AL,*XAR1++MOVW DP,#4006hADD AL,@1SUB AL,*XAR1ADD AL,*XAR2SUB AL,*+XAR2[1]ADD AL,#32SUB AL,*+XAR2[2]MOV @32h,AL

Src Mode Program

Imm: Immediate; Reg: Register;

Dir: Direct; Idr: Indirect

ACC DP XAR1 XAR2

In the table above, fill in the values for each of the registers for each of the instructions. Three areas of data memory are displayed at the top of the diagram, showing both their addresses and contents in hexadecimal. Watch out for surprises along the way. First, you should answer the addressing mode for the source operand. Then, fill in the change values as the result of the in-struction operation.


Lab B: Addressing

Lab B: Addressing Note: The lab linker command file is based on the F28035 memory map – modify as needed, if

using a different F28xx device memory map.

Objective

The objective of this lab is to practice and verify the mechanics of addressing. In this process we will expand upon the ASM file from the previous lab to include new functions. Additionally, we learn how to run and observe the operation of code using Code Composer Studio.

In this lab, we will initialize the “vars” arrays allocated in the previous lab with the contents of the “const” table. How is this best accomplished? Consider the process of loading the first “const” value into the accumulator and then storing this value to the first “vars” location, and repeating this process for each of the succeeding values.

• What forms of addressing could be used for this purpose? • Which addressing mode would be best in this case? Why? • What problems could arise with using another mode?

Procedure

Copy Files, Create Project File

1. Create a new project called LabB.pjt in C:\C28x\Labs\Appendix\LabB and add LabB.asm and Lab.cmd to it. Check your file list to make sure all the files are there. Be sure to setup the Build Options by clicking: Project Build Options on the menu bar. Select the Linker tab. In the middle of the screen select “No Autoinitialization” under “Autoinit Model:”. Enter start in the “Code Entry Point (-e):” field. Next, select the Compiler tab. Note that “Full Symbolic Debug (-g)” under “Generate Debug Info:” is selected. Then select OK to save the Build Options.

Initialize Allocated RAM Array from ROM Initialization Table 2. Edit LabB.asm and modify it to copy table[9] to data[9] using indirect addressing.

(Note: data[9] consists of the allocated arrays of data, coeff, and result). Initialize the allocated RAM array from the ROM initialization table: • Delete the NOP operations from the “code” section. • Initialize pointers to the beginning of the “const” and “vars” arrays. • Transfer the first value from “const” to the “vars” array. • Repeat the process for all values to be initialized.

To perform the copy, consider using a load/store method via the accumulator. Which part of an accumulator (low or high) should be used? Use the following when writing your copy routine: - use AR1 to hold the address of table - use AR2 to hold the address of data


Lab B: Addressing

3. It is good practice to trap the end of the program (i.e. use either “end: B end,UNC” or “end: B start,UNC”). Save your work.

Build and Load 4. Click the “Build” button and watch the tools run in the build window. Debug as

necessary. To open up more space, close any open files or windows that you do not need.

5. Load the output file onto the target. Click:

File Load Program…

If you wish, right click on the LabB.asm source window and select Mixed Mode to debug using both source and assembly.

Note: Code Composer Studio can automatically load the output file after a successful build. On the menu bar click: Option Customize… and select the “Program Load Options” tab, check “Load Program After Build”, then click OK.

6. Single-step your routine. While single-stepping, it is helpful to see the values located in table[9] and data[9] at the same time. Open two memory windows by using the “View Memory” button on the vertical toolbar and using the address labels table and data. Setting the properties filed to “Hex 16 Bit – TI style” will give you more viewable data in the window. Additionally, it is useful to watch the CPU registers. Open the CPU registers by using the “View Registers CPU Registers”. Deselect “Allow Docking” and move/resize the window as needed. Check to see if the program is working as expected.

End of Exercise


OPTIONAL Lab B-C: Array Initialization in C

OPTIONAL Lab B-C: Array Initialization in C Note: The lab linker command file is based on the F28035 memory map – modify as needed, if


Objective

The objective of this lab is to practice and verify the mechanics of initialization using C. Additionally, we learn how to run and observe the operation of C code using Code Composer Studio. In this lab, we will initialize the “vars” arrays with the contents of the “const” table.

Procedure

Create Project File

1. In Code Composer Studio create a new project called LabB-C.pjt in C:\C28x\Labs\Appendix\LabB\LabB-C and add LabB-C.c and Lab.cmd to it. Check your file list to make sure all the files are there. Open the Build Options and select the Linker tab. Select the “Libraries” Category and enter rts2800_ml.lib in the “Incl. Libraries (-l):” box. Do not setup any other Build Options. The default values will be used. In Appendix Lab D exercise, we will experiment and explore the various build options when working with C.

Initialize Allocated RAM Array from ROM Initialization Table 2. Edit LabB-C.c and modify the “main” routine to copy table[9] to the allocated arrays

of data[4], coeff[4], and result[1]. (Note: data[9] consists of the allocated arrays of data, coeff, and result).


necessary.

Note: Have Code Composer Studio automatically load the output file after a successful build. On the menu bar click: Option Customize… and select the “Program Load Options” tab, check “Load Program After Build”, then click OK.

4. Under Debug on the menu bar click “Go Main”. Single-step your routine. While single-stepping, it is helpful to see the values located in table[9] and data[9] at the same time. Open two memory windows by using the “View Memory” button on the vertical toolbar and using the address labels table and data. Setting the properties field to “Hex 16 Bit – TI style” will give you more viewable data in the window. Additionally, you can watch the CPU registers. Open the CPU registers by using the “View Registers CPU Registers. Deselect “Allow Docking” and move/resize the window as needed. Check to see if the program is working as expected.

End of Exercise


Solutions

Solutions

Exercise B: Addressing - Solution

1001B2 0320

Given: DP = 4000 DP = 4004 DP = 4006 Address/Data (hex) 100030 0025 100100 0105 100180 0100Fill in the 100031 0120 100101 0060 100181 0030table below 100032 100102 0020 100182 0040

Imm MOVW DP,#4000hMOVL XAR1,#100100hMOVL XAR2,#100180hMOV AL,@31hADD AL,*XAR1++SUB AL,@30hADD AL,*XAR1++MOVW DP,#4006hADD AL,@1SUB AL,*XAR1ADD AL,*XAR2SUB AL,*+XAR2[1]ADD AL,#32SUB AL,*+XAR2[2]MOV @32h,AL

Src Mode Program4000

Imm 100100Imm 100180Dir 120Idr 225 100101Dir 200Idr 260 100102Imm 4006Dir 290Idr 270Idr 370Idr 340Imm 360Idr 320Dir

100180

100180

ACC DP XAR1 XAR2

Imm: Immediate; Reg: Register;

Dir: Direct; Idr: Indirect


Appendix C – Assembly Programming

Introduction Appendix C discusses the details of programming in assembly. It shows you how to use different instructions that further utilize the advantage of the architecture data paths. It gives you the ability to analyze the instruction set and pick the best instruction for the application.


Perform simple program control using branch and conditional codesWrite C28x code to perform basic arithmeticUse the multiplier to implement sum-of-products equationsUse the RPT instruction (repeat) to optimize loopsUse MAC for long sum-of-productsEfficiently transfer the contents of one area of memory to anotherExamine read-modify-write operations

C2000 Piccolo Workshop - Appendix C - Assembly Programming C - 1

Module Topics

Module Topics Appendix C – Assembly Programming ...................................................................................................C-1

Module Topics.........................................................................................................................................C-2 Program Control.....................................................................................................................................C-3

Branches .............................................................................................................................................C-3 Program Control Instructions .............................................................................................................C-4

ALU and Accumulator Operations..........................................................................................................C-6 Simple Math & Shift...........................................................................................................................C-7

Multiplier ................................................................................................................................................C-9 Basic Multiplier ................................................................................................................................C-10 Repeat Instruction.............................................................................................................................C-11 MAC Instruction...............................................................................................................................C-12

Data Move.............................................................................................................................................C-13 Logical Operations ...............................................................................................................................C-15

Byte Operations and Addressing ......................................................................................................C-15 Test and Change Memory Instructions.............................................................................................C-16 Min/Max Operations.........................................................................................................................C-17

Read Modify Write Operations .............................................................................................................C-18 Lab C: Assembly Programming............................................................................................................C-20 OPTIONAL Lab C-C: Sum-of-Products in C........................................................................................C-22

C - 2 C2000 Piccolo Workshop - Appendix C - Assembly Programming

Program Control

Program Control The program control logic and program address generation logic work together to provide proper program flow. Normally, the flow of a program is sequential: the CPU executes instructions at consecutive program memory addresses. At times, a discontinuity is required; that is, a program must branch to a nonsequential address and then execute instructions sequentially at that new location. For this purpose, the C28x supports interrupts, branches, calls, returns, and repeats. Proper program flow also requires smooth flow at the instruction level. To meet this need, the C28x has a protected pipeline and an instruction-fetch mechanism that attempts to keep the pipeline full.

Branches

Branch Types and Range

Branchoffset +/-32K

2-word instruction

Long Branch

absolute 4M2-word

instruction

PC

Short Branchoffset +127/-

1281-word

instruction

ProgramMemory

0x000000

0x3FFFFF

3 Branch Types

The PC can access the entire 4M words (8M bytes) range. Some branching operations offer 8- and 16-bit relative jumps, while long branches, calls, and returns provide a full 22-bit absolute address. Dynamic branching allows a run-time calculated destination. The C28x provides the fa-miliar arithmetic results status bits (Zero, oVerflow, Negative, Carry) plus a Test Control bit which holds the result of a binary test. The states of these bits in various combinations allow a range of signed, unsigned, and binary branching conditions offered.


Program Control

Program Control Instructions

Program Control - BranchesFunction

Short Branch SB 8bit,cond 7/4 1

Fast Short Branch SBF 8bit,EQ|NEQ|TC|NTC 4/4 1

Fast Relative Branch B 16bit,cond 7/4 2

Fast Branch BF 16bit,cond 4/4 2

Absolute Branch LB 22bit 4 2

Dynamic Branch LB *XAR7 4 1

Branch on AR BANZ 16bit,ARn-- 4/2 2

Branch on compare BAR 16bit,ARn,ARn,EQ|NEQ 4/2 2

The assembler will optimize B to SB if possible

NEQEQGTGEQ

LT LEQHIHIS (C)

LO (NC)LOS NOVOV

NTCTCUNCNBIO

Condition Code

Instruction Cycles T/F Size

Condition flags are set on the prior use of the ALU

Program Control - Call/Return

Function Call Code

Call LCR 22bit 4 LRETR 4

Dynamic Call LCR *XARn 4 LRETR 4

Interrupt Return IRET 8

Cycles Return code Cycles

More Call variations in the user guide are for code backward compatibility

StackLocal

Var

RPC Old RPC

PC Func

LCR FuncLRETR

RPC22-bit old

Ret Addr

Ret AddrNew RPC


Program Control

BANZ Loop Control Example

len .set 5x .usect “samp”,6y .set (x+len)

.sect “code”MOVL XAR2,#xMOV AR3,#len-2MOV AL,*XAR2++

sum: ADD AL,*XAR2++BANZ sum,AR3--MOV *(0:y),AL

AR3COUNT

Data

x0x1x2x3x4

x

y

XAR2

∑=

=4

0nnxy

Auxiliary register used as loop counterBranch if Auxiliary Register not zeroTest performed on lower 16-bits of XARx only


ALU and Accumulator Operations


ALU and Accumulator

ALU and Barrel Shifter

ACC

AH (31-16) AL (15-0)AH.MSB AH.LSB AL.MSB AL.LSB

16/32 data mem,16/32 bit registersProduct (32)

MUX

ST0, ST1

8/16 Imm

One of the major components in the execution unit is the Arithmetic-Logical-Unit (ALU). To support the traditional Digital Signal Processing (DSP) operation, the ALU also has the zero cycle barrel shifter and the Accumulator. The enhancement that the C28x has is the additional data paths added form the ALU to all internal CPU registers and data memory. The connection to all internal registers helps the compiler to generate efficient C code. The data path to memory allows the C28x performs single atomic instructions read-modify-write to the memory.

The following slides introduce you to various instructions that use the ALU hardware. Word, byte, and long word 32-bit operation are supported.



Simple Math & Shift

Accumulator - Basic Math Instructions

MOV Ax, loc16ADD Ax, loc16SUB Ax, loc16AND Ax, loc16OR Ax, loc16XOR Ax, loc16AND Ax,loc16,#16bNOT AxNEG AxMOV loc16,Ax

Ax = AH or AL Operations

xxx Ax, #16b ;wordxxxB Ax, #8b ;bytexxxL ACC, #32b ;long

xxx = instruction: MOV, ADD, SUB, ... Ax = AH, or ALAssembler will automatically convert to 1 word instruction.

Two word instructions with shift optionOne word instruction, no shift

ADD ACC, #01234h<<4ADDB AL, #34h

ACC OperationsMOV ACC,loc16<<shiftADDSUB

} from memory (left shift optional)

MOV ACC,#16b<<shiftADDSUB } 16-bit constant (left shift

optional)

MOV loc16,ACC <<shift ;ALMOVH loc16,ACC <<shift ;AH

Form

atEx

Varia

tion

Shift the AccumulatorShift full ACCLSL ACC <<shiftSFR ACC >>shift

LSL ACC <<T SFR ACC >>T ACC

31 ……… 0SFR

ACC31 ……… 0

LSL0C

CSXM

Shift AL or AH

LSL AX <<TLSR AX <<TASR AX >>T

LSL AX <<shiftLSR AX <<shiftASR AX >>shift Ax

15 ……… 0ASR

Ax15 ……… 0 LSL

0C

CSXM

Ax15 ……… 0

LSRC0

(1-16)

(0-15)



32 Bit Shift Operations [ACC]

ACC31 ……… 0

0CExamples:LSLL ACC, T

LSRL ACC, TASRL ACC, T

ACC31 ……… 0

C0 or 1

ACC31 ……… 0

C0

Note: T(4:0) are used;other bits are ignored

based on SXM

Logical Shift Left – Long: LSLL

Logical Shift Right – Long: LSRL

Arithmetic Shift Right – Long: ASRL


Multiplier

Multiplier

Multiply Unit

P Register (32)

ACC (32)

Shift (PM)

32x32 Multiply Unit

16x16

Data Memor Register

Prog Mem (16)or

Immed (8,16)

XT Register

MU

X

T Register

Digital signal processors require many multiply and add math intensive operations. The single cycle multiplier is the second major component in the execution unit. The C28x has the traditional 16-bit-by-16-bit multiplier as previous TI DSP families. In-addition, the C28x has a single cycle 32-bit-by-32-bit multiplier to perform extended precision math operations. The large multiplier allows the C28x to support higher performance control systems requirement while maintaining small or reduce code.

The following slides introduce instructions that use the 16-bit-by-16-bit multiplier and multiply and add (MAC) operations. The 32-bit-by-32-bit multiplication will be covered in the appendix.


Multiplier

Basic Multiplier

Multiplier InstructionsInstruction Execution Purpose

MOV T,loc16 T = loc16 Get first operand

MPY ACC,T,loc16 ACC = T*loc16 For single or first productMPY P,T,loc16 P = T*loc16 For nth productMPYB ACC,T,#8bu ACC = T*8bu Using 8-bit unsigned constMPYB P,T,#8bu P = T*8bu Using 8-bit unsigned constMOV ACC,P ACC = P Move 1st product<<PM to ACCADD ACC,P ACC += P Add nth product<<PM to ACCSUB ACC,P ACC -= P Sub nth product<<PM fr. ACC

Instruction

MPYA P, T, #16b ACC += P<<PM then P = T*#16bMPYA P, T, loc16 ACC += P<<PM then P = T*loc16MPYS P, T, loc16 ACC - = P<<PM then P = T*loc16

ExecutionMOVP T, loc16 ACC = P<<PM T = loc16MOVA T, loc16 ACC += P<<PM T = loc16MOVS T, loc16 ACC - = P<<PM T = loc16

Sum-of-Products

ZAPA ;ACC = P = OVC = 0MOV T,@X1 ;T = X1MPY P,T,@A ;P = A*X1 MOVA T,@X2 ;T = X2 ;ACC = A*X1MPY P,T,@B ;P = B*X2MOVA T,@X3 ;T = X3 ;ACC = A*X1 + B*X2 MPY P,T,@C ;P = C*X3MOVA T,@X4 ;T = X4;ACC = A*X1 + B*X2 + C*X3 MPY P,T,@D ;P = D*X4ADDL ACC,P<<PM ;ACC = YMOVL @y,ACC

Y = A*X1 + B*X2 + C*X3 + D*X4


Multiplier

32x32 Long Multiplication

IMPYAL P,XT,loc32 P = u(XT)*u(loc32)QMPYAL ACC,XT,loc32 ACC = (XT)*(loc32)

X

YX

XO * Y0

Z1 Z0

IMACL P,loc32,*XAR7 ACC += P; P = u(loc32)*u(loc32)QMACL P,loc32,*XAR7 ACC += P; P = (loc32)*(loc32)

Integer long multiplicationu(long) = u(long) * u(long)

Fraction long multiplication: (long) = (long) * (long)(long) 64 = (long) 32 * (long) 32

Y1 * X1

Z3 Z2

Accumulator P-register

Repeat Instruction

Repeat Next: RPT

Features:Next instruction iterated N+1 timesSaves code space - 1 wordLow overhead - 1 cycleEasy to use Non-interruptibleRequires use of | | before next lineMay be nested within BANZ loops

Options:RPT #8bit up to 256 iterationsRPT loc16 location “loc16” holds count value

Instruction CyclesRPTBANZ

14 . N

Example :int x[5]={0,0,0,0,0};

x .usect “samp”,5MOV AR1,#xRPT #4

|| MOV *XAR1++,#0

Refer to User Guide for more repeatable instructions


Multiplier

Single repeat instruction (RPT) is used to reduce code size and speed up many operations in the DSP application. Some of the most popular operations that use the RPT instruction to perform multiple taps digital filters or perform block of data transfer.

MAC Instruction

Sum-of-Products: RPT / MAC

∑=

=19

0nnnaxy

XAR1++ X0

X1

...

X19

MOV T,loc16ADD ACC,P MPY P,T,loc16

MOVA T,loc16 ACC+=PT=*ARn++P=T*(*ARn++)

MAC {

Zero ACC & PRepeat singleDual operandlast ADD

ZAPARPT #19

|| MAC P,*XAR1++,*XAR7++ADDL ACC,P<<PM

x .usect “sample”,20y .usect “result”,2

.sect “coefficient”a0: .word 0x0101

.word 0x0202• • •

.word 0x2020

.sect “code”SOP: SPM 0

MOVW DP,#yMOVL XAR1,#xMOVL XAR7,#a0

MOVL @y,ACCB SOP,UNC

XAR7++ A0

A1

...

A19

Second operand must use XAR7


Data Move

Data Move

Data Move InstructionsDATA ↔ DATA (4G ↔ 64K) DATA ↔ PGM (4G ↔ 4M)

Faster than Load / Store, avoids accumulatorAllows access to program memory

Optimal with RPT (speed and code size) In RPT, non-mem address is auto-incremented in PC

MOV loc16, *(0:16bit)

MOV *(0:16bit), loc16

32-bit address memory location

16-bit address concatenated with 16 leading zeros

.sect “.code”START: MOVL XAR5,#x

MOVL XAR7,#TBLRPT #len-1

|| PREAD *XAR5++,*XAR7...

x .usect “.samp”,4.sect “.coeff”

TBL: .word 1,2,3,4len .set $-TBL

PREAD loc16 ,*XAR7

PWRITE *XAR7, loc16

pointer with a 22-bit program memory address

Conditional MovesInstruction Execution (if COND is met)MOV loc16,AX,COND [loc16] = AX

MOVB loc16,#8bit,COND [loc16] = 8bit

If A<B, Then B=A Accumulator0 0 0 0 0 1 2 0

MOVW DP, #AMOV AL, @ACMP AL, @B

Example

A .usect “var”,2,1B .set A+1

.sect “code”

MOV @B, AL, LT

0 1 2 00 3 2 0

Data Memory

BA 0 1 2 0

Data Memory

BA

0 1 2 0

Before After

Instruction Execution (if COND is met)MOVL loc32,ACC,COND [loc32] = AX

The conditional move instruction is an excellent way to avoid a discontinuity (branch or call) based upon a condition code set prior to the instruction. In the above example, the 1st step is to


Data Move

place the contents of A into the accumulator. Once the Ax content is tested, by using the CMP instruction, the conditional move can be executed. If the specified condition being tested is true, then the location pointed to by the “loc16” address-ing mode or the 8–bit zero extended constant will be loaded with the contents of the specified AX register (AH or AL): if (COND == true) [loc16] = AX or 0:8bit; Note: Addressing modes are not conditionally executed. Hence, if an addressing mode performs a pre or post modification, it will execute regardless if the condition is true or not. This instruction is not repeatable. If this instruction follows the RPT instruction, it resets the repeat counter (RPTC) and executes only once. Flags and Modes N - If the condition is true, then after the move, AX is tested for a negative condition. The nega-tive flag bit is set if bit 15 of AX is 1, otherwise it is cleared. Z - If the condition then after the move, AX is tested for a zero condition. The zero flag bit is set if AX = 0, otherwise it is cleared. V - If the V flag is tested by the condition, then V is cleared. C-Example ; if ( VarA > 20 ) ; VarA = 0; CMP @VarA,#20 ; Set flags on (VarA – 20) MOVB @VarA,#0,GT ; Zero VarA if greater then


Logical Operations

Logical Operations

Byte Operations and Addressing

Byte Operations

MOVB AX.LSB,loc16 0000 0000 Byte AX

MOVB AX.MSB,loc16 Byte No change AX

MOVB loc16, AX.MSB Byte loc16No change

MOVB loc16, AX.LSB Byte loc16No change

For loc16 = *+XARn[Offset] Odd Offset Even Offset loc16

Byte = 1. Low byte for register addressing2. Low byte for direct addressing3. Selected byte for offset indirect addressing

Byte Addressing

MOVL XAR2, #MemAMOVB *+XAR2[1], AL.LSBMOVB *+XAR2[2], AL.MSBMOVB *+XAR2[5], AH.LSBMOVB *+XAR2[6], AH.MSB

AR2

AH.MSB AH.LSB AL.MSB AL.LSB

16 bit memory

0102

0506

12 34 56 78

0407

000334

56

12

78

MOVL XAR2, #MemAMOVB AL.LSB,*+XAR2[1]MOVB AL.MSB,*+XAR2[2]MOVB AH.LSB,*+XAR2[4]MOVB AH.MSB,*+XAR2[7]

Example of Byte PackingExample of Byte Un-Packing


Logical Operations

Test and Change Memory Instructions The compare (CMPx) and test (Txxx) instructions allow the ability to test values in memory. The results of these operations can then trigger subsequent conditional branches. The CMPx instruc-tion allows comparison of memory with respect to a specified constant value, while the Txxx in-structions allow any single bit to be extracted to the test control (TC) field of status register 0. The contents of the accumulator can also be non-destructively analyzed to establish branching conditions, as seen below.

Test and Change Memory

Instruction Execution AffectsTBIT loc16,#(0-15) ST0(TC) = loc16(bit_no) TC

TSET loc16,#(0-15) Test (loc16(bit)) then set bit TCTCLR loc16,#(0-15) Test (loc16(bit)) then clr bit TCCMPB AX, #8bit Test (AX - 8bit unsigned) C,N,ZCMP AX, loc16 Test (AX – loc16) C,N,ZCMP loc16,#16b Test (loc16 - #16bit signed) C,N,ZCMPL ACC, @P Test (ACC - P << PM) C,N,Z


Logical Operations

Min/Max Operations

MIN/MAX Operations

MOVL ACC,#0MOVL XAR1,#tableRPT #(table_length – 1)

|| MAXL ACC,*XAR1++

Find the maximum 32-bit number in a table:

Instruction ExecutionMAX ACC,loc16 if ACC < loc16, ACC = loc16

if ACC >= loc16, do nothingMIN ACC,loc16 if ACC > loc16, ACC = loc16

if ACC <= loc16, do nothingMAXL ACC,loc32 if ACC < loc32, ACC = loc32

if ACC >= loc32, do nothingMINL ACC,loc32 if ACC > loc32, ACC = loc32

if ACC <= loc32, do nothingMAXCUL P,loc32 if P < loc32, P = loc32(for 64 bit math) if P >= loc32, do nothingMINCUL P,loc32 if P > loc32, P = loc32(for 64 bit math) if P <= loc32, do nothing


Read Modify Write Operations

Read Modify Write Operations The accumulator (ACC) is the main working register for the C28x. It is the destination of all ALU operations except those, which operate directly on memory or registers. The accumulator supports single-cycle move, add, subtract and compare operations from 32-bit-wide data memory. It can also accept the 32-bit result of a multiplication operation. These one or two cycle operations are referred to as read-modify-write operations, or as atomic instructions.

Read-Modify-Write Instructions

AND loc16,#16b

OR loc16,#16b

XOR loc16,#16b

ADD loc16,#16b

SUBR loc16,#16b

AND loc16,AX

OR loc16,AX

XOR loc16,AX

ADD loc16,AX

SUB loc16,AX

SUBR loc16,AXINC loc16

DEC loc16

TSET loc16,#bit

TCLR loc16,#bit

AH, AL

16- bit constant

Work directly on memory – bypass ACCAtomic Operations – protected from interrupts


Read Modify Write Operations

Read-Modify-Write Examples

MOV AL, @VarB

ADD @VarA, AL

VarA += VarB VarA += 100 VarA += 1

ADD @VarA,#100 INC @VarA

SETC INTM

MOV AL, @VarB

ADD AL, @VarA

MOV @VarA, AL

CLRC INTM

SETC INTM

MOV AL, @VarA

ADD AL, #100

MOV @VarA, AL

CLRC INTM

SETC INTM

MOV AL, @VarA

ADD AL, #1

MOV @VarA, AL

CLRC INTM

update with a mem update with a constant update by 1

Benefits of Read-Modify-Write Instructions


Lab C: Assembly Programming

Lab C: Assembly Programming Note: The lab linker command file is based on the F28035 memory map – modify as needed, if


Objective

The objective of this lab is to practice and verify the mechanics of performing assembly language programming arithmetic on the TMS320C28x. In this exercise, we will expand upon the .asm file from the previous lab to include new functions. Code will be added to obtain the sum of the products of the values from each array.

Perform the sum of products using a MAC-based implementation. In a real system application, the coeff array may well be constant (values do not change), therefore one can modify the initialization routine to skip the transfer of this arrays, thus reducing the amount of data RAM and cycles required for initialization. Also there is no need to copy the zero to clear the result location. The initialization routine from the previous lab using the load/store operation will be replaced with a looped BANZ implementation.

As in previous lab, consider which addressing modes are optimal for the tasks to be performed. You may perform the lab based on this information alone, or may refer to the following procedure.

Procedure


1. Create a new project called LabC.pjt in C:\C28x\Labs\Appendix\LabC and add LabC.asm and Lab.cmd to it. Check your file list to make sure all the files are there. Be sure to setup the Build Options by clicking: Project Build Options on the menu bar. Select the Linker tab. In the middle of the screen select “No Autoinitialization” under “Autoinit Model:”. Enter start in the “Code Entry Point (-e):” field. Next, select the Compiler tab. Note that “Full Symbolic Debug (-g)” under “Generate Debug Info:” is selected. Then select OK to save the Build Options.

Initialization Routine using BANZ 2. Edit LabC.asm and modify it by replacing the initialization routine using the load/store

operation with a BANZ process. Remember, it is only necessary to copy the first four values (i.e. initialize the data array). Do you still need the coeff array in the vars section?

3. Save your work. If you would like, you can use Code Composer Studio to verify the correct operation of the block initialization before moving to the next step.


Lab C: Assembly Programming

Sum of Products using a RPT/MAC-based Implementation 4. Edit LabC.asm to add a RPT/MAC-based implementation to multiply the coeff array by

the data array and storing the final sum-of-product value to result.


necessary. To open up more space, close any open files or windows that you do not need.

6. If the “Load program after build” option was not selected in Code Composer Studio, load the output file onto the target. Click: File Load Program…

If you wish, right click on the source window and select Mixed Mode to debug using both source and assembly.

7. Single-step your routine. While single-stepping, open memory windows to see the values located in table [9] and data [9]. Open the CPU Registers. Check to see if the program is working as expected. Debug and modify, if needed.

Optional ExerciseAfter completing the above, edit LabC.asm and modify it to perform the initialization process using a RTP/PREAD rather than a load/store/BANZ.

End of Exercise


OPTIONAL Lab C-C: Sum-of-Products in C

OPTIONAL Lab C-C: Sum-of-Products in C Note: The lab linker command file is based on the F28035 memory map – modify as needed, if


Objective

The objective of this lab is to practice and verify the mechanics of performing C programming arithmetic on the TMS320C28x. The objective will be to add the code necessary to obtain the sum of the products of the n-th values from each array.

Procedure

Create Project File

1. In Code Composer Studio create a new project called LabC-C.pjt in C:\C28x\Labs\Appendix\LabC\LabC-C and add LabC-C.c and Lab.cmd to it. Check your file list to make sure all the files are there. Open the Build Options and select the Linker tab. Select the “Libraries” Category and enter rts2800_ml.lib in the “Incl. Libraries (-l):” box. Do not setup any other Build Options. The default values will be used. In Appendix Lab D exercise, we will experiement and explore the various build options when working with C.

Sum of Products using a MAC-based Implementation 2. Edit LabC-C.c and modify the “main” routine to perform a MAC-based

implementation in C. Since the MAC operation requires one array to be in program memory, the initialization routine can skip the transfer of one of the arrays, thus reducing the amount of data RAM and cycles required for initialization.


necessary.

Note: Have Code Composer Studio automatically load the output file after a successful build. On the menu bar click: Option Customize… and select the “Program Load Options” tab, check “Load Program After Build”, then click OK.

4. Under Debug on the menu bar click “Go Main”. Single-step your routine. While single-stepping, open memory windows to see the values located in table [9] and data [9] . (Note: data[9] consists of the allocated arrays of data, coeff, and result). Open the CPU Registers. Check to see if the program is working as expected. Debug and modify, if needed.

End of Exercise


Appendix D – C Programming

Introduction The C28x architecture, hardware, and compiler have been designed to efficiently support C code programming. Appendix D will focus on how to program in C for an embedded system. Issues related to programming in C and how C behaves in the C28x environment will be discussed. Also, the C compiler optimization features will be explained.

Learning Objectives

Learning Objectives

Learn the basic C environment for the C28x familyHow to control the C environmentHow to use the C-compiler optimizerDiscuss the importance of volatileExplain optimization tips

C2000 Piccolo Workshop – Appendix D – C Programming D- 1

Module Topics

Module Topics Appendix D – C Programming.................................................................................................................D-1

Module Topics.........................................................................................................................................D-2 Linking Boot code from RTS2800.lib ......................................................................................................D-3 Set up the Stack .......................................................................................................................................D-4 C28x Data Types.....................................................................................................................................D-5 Accessing Interrupts / Status Register.....................................................................................................D-6 Using Embedded Assembly .....................................................................................................................D-7 Using Pragma .........................................................................................................................................D-8 Optimization Levels ................................................................................................................................D-9

Volatile Usage ..................................................................................................................................D-11 Compiler Advanced Options ............................................................................................................D-12 Optimization Tips Summary.............................................................................................................D-13

Lab D: C Optimization..........................................................................................................................D-14 OPTIONAL Lab D2: C Callable Assembly...........................................................................................D-17 Solutions................................................................................................................................................D-20

D- 2 C2000 Piccolo Workshop – Appendix D – C Programming

Linking Boot code from RTS2800.lib

Linking Boot code from RTS2800.lib Boot.ASM - Invoked With “-C”

Reset : PC <- *0x3F FFC0

_main ...

1. Allocate stack2. Init SP to top of stack3. Initialize status bits4. Copy .cinit to .bss (skip if “-cr”)5. Call “_main”

_c_int00

.ref _c_int00Reset:

.long _c_int00

vectors.asm

The boot routine is used to establish the environment for C before launching main. The boot routine begins with the label _c_int00 and the reset vector should contain a ".long" to this address to make boot.asm the reset routine. The contents of the boot routine have been extracted and copied on the following page so they may be inspected. Note the various functions performed by the boot routine, including the allocation and setup of the stack, setting of various C-requisite statuses, the initialization of global and static variables, and the call to main. Note that if the link was performed using the "–cr" option instead of the "–c" option that the global/static variable initialization is not performed. This is useful on RAM-based C28x systems that were initialized during reset by some external host processor, making transfer of initialization values unnecessary. Later on in this chapter, there is an example on how to do the vectors in C code rather than assembly.

C2000 Piccolo Workshop – Appendix D – C Programming D - 3

Set up the Stack

Set up the Stack The Stack

The C/C++ compiler uses a stack to:Allocate local variablesPass arguments to functionsSave the processor statusSave the function return addressSave temporary results

The compiler uses the hardware stack pointer (SP) to manage the stack.

SP defaults to 0x400 at reset.The run-time stack grows from

low addresses to higher addresses.

Data Memory

64K

0x400SP (reset)

.stack

4M

Caller’s local vars

Arguments passed on

stackReturn address

Function return addr

Temp results

The C28x has a 16-bit stack pointer (SP) allowing accesses to the base 64K of memory. The stack grows from low to high memory and always points to the first unused location. The compiler uses the hardware stack pointer (SP) to manage the stack. The stack size is set by the linker.

Setting Up the StackBoot.asm sets up SP to point at .stackThe .stack section has to be linked into the low 64k of data memory. The SP is a 16-bit register and cannot access addresses beyond 64K.Stack size is set by the linker. The linker creates a global symbol, --STACK-SIZE, and assigns it a value equal to the size of the stack in bytes. (default 1K words)You can change stack size at link time by using the -stack linker command option.

Linker command file:SECTIONS {.stack :> RAM align=2

... }

Note: The compiler provides no means to check for stack overflow during compilation or at runtime. A stack overflow disrupts the run-time environment, causing your program to fail. Be sure to allow enough space for the stack to grow.

In order to allocate the stack the linker command file needs to have “align = 2.”


C28x Data Types

C28x Data Types C28x C-Language Data Types

Type Bit Value Range

char 16 Usually 0 .. 255, but can hold 16 bitsint (natural size CPU word) 16 -32K .. 32K, 16 bits signedunsigned int 16 0 .. 64K, 16 bits unsignedshort (same as int or smaller) 16 same as intunsigned short 16 same as unsigned int

long (same as int or larger) 32 -2M .. 2M, 32 bits signedunsigned long 32 0 .. 4M, 32 bits unsigned

float 32 IEEE single precision double 64 IEEE double precisionlong double 64 IEEE double precision

Data which is 32-bits wide, such as longs, must begin on even word-addresses (i.e. 0x0, 0x2, etc). This can result in “holes” in structures allocated on the stack.

Suggestion: Group all longs together, group all pointers together


Accessing Interrupts / Status Register

Accessing Interrupts / Status Register Accessing Interrupts / Status RegisterInitialize via C :extern cregister volatile unsigned int IFR;extern cregister volatile unsigned int IER;. . .IER &= ~Mask; //clear desired bitsIER |= Mask; //set desired bitsIFR = 0x0000; //clear prior interrupts

Interrupt Enable & Interrupt Flag Registers (IER, IFR) are not memory mapped

Only limited instructions can access IER & IFR (more in interrupt chapter)

The compiler provides extern variables for accessing the IER & IFR


Using Embedded Assembly

Using Embedded Assembly

Embedding Assembly in C

Allows direct access to assembly language from CUseful for operating on components not used by C, ex:

asm ( “ CLRC INTM ; enable global interrupt” );

Note: first column after leading quote is label field - if no label, should be blank space.Avoid modifying registers used by CLengthy code should be written in ASM and called from C

main C file retains portabilityyields more easily maintained structureseliminates risk of interfering with registers in use by C

#define EINT asm ( “ CLRC INTM”)

The assembly function allows for C files to contain 28x assembly code. Care should be taken not to modify registers in use by C, and to consider the label field with the assembly function. Also, any significant amounts of assembly code should be written in an assembly file and called from C. There are two examples in this slide – the first one shows how to embed a single assembly language instruction into the C code flow. The second example shows how to define a C term that will invoke the assembly language instruction.


Using Pragma

Using Pragma Pragma is a preprocessor directive that provides directions to the compiler about how to treat a particular statement. The following example shows how the DATA_SECTION pragma is used to put a specific buffer into a different section of RAM than other buffers.

The example shows two buffers, bufferA and bufferB. The first buffer, bufferA is treated normally by the C compiler by placing the buffer (512 words) into the ".bss" section. The second, bufferB is specifically directed to go into the “my_sect” portion of data memory. Global variables, normally ".bss", can be redirected as desired.

When using CODE_SECTION, code that is normally linked as ".text", can be identified otherwise by using the code section pragma (like .sect in assembly).

#pragma CODE_SECTION (func, ”section name”)

#pragma DATA_SECTION (symbol, “section name”)

User defined sections from C :

Pragma Examples

.global _bufferA, _bufferB

.bss _bufferA,512_bufferB: .usect “my_sect”,512

Resulting assembly file

char bufferA[512];#pragma DATA_SECTION(bufferB, ”my_sect”)char bufferB[512];

C source file

Example - using the DATA_SECTION Pragma

More #pragma are defined in the C compiler UG


Optimization Levels

Optimization Levels Optimization Scope

FILE1.C{

{SESE

}

{. . .

}}

{. . .

}

FILE2.C

-o0, -o1 -o2 -o3 -pm -o3

SESE: Single Entry, Single Exit

LOCALsingle block

FUNCTIONacrossblocks

FILEacross

functions PROGRAMacross files

{. . .

}

Optimizations fall into 4 categories. This is also a methodology that should be used to invoke the optimizations. It is recommended that optimization be invoked in steps, and that code be verified before advancing to the next step. Intermediate steps offer the gradual transition from fully sym-bolic to fully optimized compilation. Compiler switched may be invoked in a variety of ways. Here are 4 steps that could be considered: 1st: use –g By starting out with –g, you do no optimization at all and keep symbols for debug. 2nd: use –g –o3 The option –o3 might be too big a jump, but it adds the optimizer and keeps symbols. 3rd: use –g –o3 –mn This is a full optimization, but keeps some symbols 4th: use –o3 Full optimization, symbols are not kept.


Optimization Levels

Optimization Performance

–o3 Removes all functions that are never calledSimplifies functions with return values that are never usedInlines calls to small functionsIdentifies file-level variable characteristics

–o0 Performs control-flow-graph simplificationAllocates variables to registersPerforms loop rotationEliminates unused codeSimplifies expressions and statementsExpands calls to functions declared inline

–o1 Performs local copy/constant propagationRemoves unused assignmentsEliminates local common expressions

–o2 Default (-o)Performs loop optimizationsEliminates global common sub-expressionsEliminates global unused assignments

FUNCTION

LOCAL

FILE

PROGRAM –o3 –pm

Optimizer levels zero through three, offer an increasing array of actions, as seen above. Higher levels include all the functions of the lower ones. Increasing optimizer levels also increase the scope of optimization, from considering the elements of single entry, single-exit functions only, through all the elements in a file. The “-pm” option directs the optimizer to view numerous input files as one large single file, so that optimization can be performed across the whole system.


Optimization Levels

Volatile Usage

Optimization Issue: “Volatile” Variables

unsigned int *CTRLwhile (*CTRL !=1);

volatile unsigned int *CTRLwhile (*CTRL !=1);

Wrong: Wait loop for a hardware signal

Solution:

Problem: The compiler does not know that this pointer may refer to a hardware register that may change outside the scope of the C program. Hence it may be eliminated (optimized out of existence!)

CTRL = 1?

No

Yes

Optimizer removes empty loop

emptyloop

When using optimization, it is important to declare variables asvolatile when:

The memory location may be modifed by something other than the compiler (e.g. it’s a memory-mapped peripheral register).The order of operations should not be rearranged by the compiler

Define the pointer as “volatile” to prevent the optimizer from optimizing


Optimization Levels

Compiler Advanced Options To get to these options, go to Project Build Options in Code Composer Studio.

In the category, pick Advanced. The first thing to notice under advanced options is the Auto Inlining Threshold.

- Used with –o3 option

- Functions > size are not auto inlined

Note: To prevent code size increases when using –o3, disable auto inlining with -oi0

The next point we will cover is the Normal Optimization with Debug (-mn). - Re-enables optimizations disabled by “–g” option (symbolic debug)

- Used for maximum optimization Note: Some symbolic debug labels will be lost when –mn option is used. Optimizer should be invoked incrementally: -g test Symbols kept for debug

-g -o3 test Add optimizer, keep symbols

-g -o3 -mn test More optimize, some symbols

-o3 test Final rev: Full optimize, no symbols

[-mf] : Optimize for speed instead of the default optimization for code size

[-mi] : Avoid RPT instruction. Prevent compiler from generating RPT instruction. RPT instruc-tion is not interruptible [-mt] : Unified memory model. Use this switch with the unified memory map of the 281x & 280x. Allows compiler to generate the following:

-RPT PREAD for memory copy routines or structure assignments -MAC instructions -Improves efficiency of switch tables


Optimization Levels

Optimization Tips Summary

Summary: Optimization TipsWithin C functions :

Use const with variables for parameter constantsMinimize mixing signed & unsigned ops Keep frames <= 64 (locals + parameters + PC) Use structures <= 8 words Declare longs first, then declare intsAvoid: long = (int * int)

Optimizing : Use -o0, -o1, -o2, -o3 when compilingInline short/key functionsPass inlines between files : static inlines in header filesInvoke automatic inlining : -o3 -oiGive compiler project visibility : use -pm and -o3

Tune memory map via linker command fileRe-write key code segments to use intrinsics or in assembly

App notes 3rd Parties

: SXM changes: *-SP[6bit]

: use 3 bit index mode : minimize stack holes

: yields unpredictable results

The list above documents the steps that can be taken to achieve increasingly higher coding effi-ciency. It is recommended that users first get their code to work with no optimization, and then add optimizations until the required performance is obtained.


Lab D: C Optimization

Lab D: C Optimization Note: The lab linker command file is based on the F28035 memory map – modify as needed, if


Objective

The objective of this lab is to practice and verify the mechanics of optimizing C programs. Using Code Composer Studio profile capabilities, different routines in a project will be benchmarked. This will allow you to analyze the performance of different functions. This lab will highlight the profiler and the clock tools in CCS.

Procedure

Create Project File

1. Create a new project in C:\C28x\Labs\Appendix\LabD called LabD.pjt and add LabD.c, Lab.cmd, and sop-c.c to it. (Note that sop-asm.asm will be used in the next part of the lab, and should not be added now).

2. Setup the Build Options. Select the Linker tab and notice that “Run-time Autoinitialization” under “Autoinit Model:”is selected. Do not enter anything in the “Code Entry Point (-e):” field (leave it blank). Set the stack size to 0x200. In the Linker options select the “Libraries” Category and enter rts2800_ml.lib in the “Incl. Libraries (-l):” box. Next, select the Compiler tab. Note that “Full Symbolic Debug (-g)” under “Generate Debug Info:” in the Basic Category is selected. On the Feedback Category pull down the interlisting options and select “C and ASM (-ss)”. On the Assembly Category check the Keep generated .asm Files (-k), Keep Labels as Symbols (-as) and Generate Assembly Listing Files (-al). The –as will allow you to see symbols in the memory window and the –al will generate an assembly listing file (.lst file). The listing file has limited uses, but is sometime helpful to view opcode values and instruction sizes. (The .lst file can be viewed with the editor). Both of these options will help with debugging. Then select OK to save the Build Options.

Build and Load 3. Click the “Build” button and watch the tools run in the build window. Be sure the

“Load program after build” option is selected in Code Composer Studio. The output file should automatically load. The Program Counter should be pointing to _c_int00 in the Disassembly Window.

Set Up the Profile Session 4. Restart the DSP (debug restart) and then “Go Main”. This will run

through the C initialization routine in Boot.asm and stop at the main routine in LabD.c.



5. Set a breakpoint on the NOP in the while(1) loop at the end of main() in LabD.c.

6. Set up the profile session by selecting Profiler Start New Session. Enter a session name of your choice (i.e. LabD).

7. In the profiler window, hover the mouse over the icons on the left region of the window and select the icon for Profile All Functions. Click on the “+” to expand the functions. Record the “Code Size” of the function sop C code in the table at the end of this lab. Note: If you do not see a “+” beside the .out file, press “Profile All Functions” on the horizontal tool bar. (You can close the build window to make the profiler window easier to view by right clicking on the build window and selecting “hide”).

8. Select F5 or the run icon. Observe the values present in the profiling window. What do the numbers mean? Click on each tab to determine what each displays.

Benchmarking Code9. Let’s benchmark (i.e.count the cycles need by) only a portion of the code. This requires

you to set a breakpoint pair on the starting and ending points of the benchmark. Open the file sop-c.c and set a breakpoint on the “for” statement and the “return” statement.

10. In CCS, select Profile Setup. Check “Profile all Functions and Loops for Total Cycles” and click “Enable Profiling”. Then select Profile viewer.

11. Now “Restart” the program and then “Run” the program. The program should be stopped at the first breakpoint in sop. Double click on the clock window to set the clock to zero. Now you are ready to benchmark the code. “Run” to the second breakpoint. The number of cycles are displayed in the viewer window. Record this value in the table at the end of the lab under “C Code - Cycles”.

C Optimization 12. To optimize C code to the highest level, we must set up new Build Options for our

Project. Select the Compiler tab. In the Basic Category Panel, under “Opt Level” select File (-o3). Then select OK to save the Build Options.

13. Now “Rebuild” the program and then “Run” the program. The program should be stopped at the first breakpoint in sop. Double click on the clock window to set the clock to zero. Now you are ready to benchmark the code. “Run” to the second breakpoint. The number of cycles are displayed in the clock window. Record this value in the table at the end of the lab under “Optimized C (-o3) - Cycles”.

14. Look in your profile window at the code size of sop. Record this value in the table at the end of this lab.

Benchmarking Assembly Code 15. Remove sop-c.c from your project and replace it with sop-asm.asm. Rebuild

and set breakpoints at the beginning and end of the assembly code (MOVL & LRETR).



16. Start a new profile session and set it to profile all functions. Run to the first breakpoint and study the profiler window. Record the code size of the assembly code in the table.

17. Double Click on the clock to reset it. Run to the last breakpoint. Record the number of cycles the assembly code ran.

18. How does assembly, C code, and optimized C code compare on the C28x?

C Code Optimized C Code (-o3) Assembly Code

Code Size

Cycles

End of Exercise


OPTIONAL Lab D2: C Callable Assembly

OPTIONAL Lab D2: C Callable Assembly Note: The lab linker command file is based on the F28035 memory map – modify as needed, if


Objective

The objective of this lab is to practice and verify the mechanics of implementing a C callable assembly programming. In this lab, a C file will be used to call the sum-of-products (from the previous Appendix LabC exercise) by the “main” routine. Additionally, we will learn how to use Code Composer Studio to configure the C build options and add the run-time support library to the project. As in previous labs, you may perform the lab based on this information alone, or may refer to the following procedure.

Procedure


1. Create a new project in C:\C28x\Labs\Appendix\LabD2 called LabD2.pjt and add LabD2.c, Lab.cmd, and sop-c.c to it.

2. Do not add LabC.asm to the project (copy of file from Appendix Lab C). It is only placed here for easy access. Parts of this file will be used later during this lab exercise.

3. Setup the Build Options. Select the Linker tab and notice that “Run-time Autoinitialization” under “Autoinit Model:”is selected. Do not enter anything in the “Code Entry Point (-e):” field (leave it blank). Set the stack size to 0x200. In the Linker options select the “Libraries” Category and enter rts2800_ml.lib in the “Incl. Libraries (-l):” box. Next, select the Compiler tab. Note that “Full Symbolic Debug (-g)” under “Generate Debug Info:” in the Basic Category is selected. On the Feedback Category pull down the interlisting options and select “C and ASM (-ss)”. On the Assembly Category check the Keep generated .asm Files (-k), Keep Labels as Symbols (-as) and Generate Assembly Listing Files (-al). The –as will allow you to see symbols in the memory window and the –al will generate an assembly listing file (.lst file). The listing file has limited uses, but is sometime helpful to view opcode values and instruction sizes. (The .lst file can be viewed with the editor). Both of these options will help with debugging. Then select OK to save the Build Options.

Build and Load 4. Click the “Build” button and watch the tools run in the build window. Be sure the

“Load program after build” option is selected in Code Composer Studio. The output file should automatically load. The Program Counter should be pointing to _c_int00 in the Disassembly Window.

5. Under Debug on the menu bar click “Go Main”. This will run through the C initialization routine in Boot.asm and stop at the main routine in LabD2.c.



Verify C Sum of Products Routine 6. Debug using both source and assembly (by right clicking on the window and select

Mixed Mode or using View → Mixed Source/ASM).

7. Open a memory window to view result and data.

8. Single-step through the C code to verify that the C sum-of-products routine produces the results as your assembly version.

Viewing Interlisted Files and Creating Assembly File 9. Using File → Open view the LabD2.asm and sop-c.asm generated files. The

compiler adds many items to the generated assembly file, most are not needed in the C-callable assembly file. Some of the unneeded items are .func / .endfunc. .sym, and .line.

10. Look for the _sop function that is generated by the compiler. This code is the basis for the C-callable assembly routine that is developed in this lab. Notice the comments generated by the compiler on which registers are used for passing parameters. Also, notice the C code is kept as comments in the interlisted file.

11. Create a new file (File → New, or clicking on the left most button on the horizontal toolbar “New”) and save it as an assembly source file with the name sop-asm.asm. Next copy ONLY the sum of products function from LabC.asm into this file. Add a _sop label to the function and make it visible to the linker (.def). Also, be sure to add a .sect directive to place this code in the “code” section. Finally, add the following instruction to the end:

LRETR ; return statement

12. Next, we need to add code to initialize the sum-of-products parameters properly, based on the passed parameters. Add the following code to the first few lines after entering the _sop routine: (Note that the two pointers are passed in AR4 and AR5, but one needs to be placed in AR7. The loop counter is the third argument, and it is passed in the accumulator.)

MOVL XAR7,XAR5 ;XAR7 points to coeff [0]

MOV AR5,AL ;move n from ACC to AR5 (loop counter)

SUBB XAR5,#1 ;subtract 1 to make loop counter = n-1

Before beginning the MAC loop, add statements to set the sign extension mode, set the SPM to zero, and a ZAPA instruction. Use the same MAC statement as in Lab 4, but use XAR4 in place of XAR2. Make the repeat statement use the passed value of n-1 (i.e. AR5).

RPT AR5 ;repeat next instruction AR5 times



Now we need to return the result. To return a value to the calling routine you will need to place your 32-bit value in the ACC. What register is the result currently in? Adjust your code, if necessary.

13. Save the assembly file as sop-asm.asm. (Do not name it LabD2.asm because the compiler has already created with that name from the original LabD2.c code).

Defining the Function Prototype as External 14. Note in LabD2.c an “extern” modifier is placed in front of the sum-of-products function

prototype:

extern int sop(int*,int*,int); //sop function prototype

Verify Assembly Sum of Products Routine 15. Remove the sop-c.c file from the project and add the new sop-asm.asm assembly

file to the project.

16. Rebuild and verify that the new assembly sum-of-products routine produces the same results as the C function.

End of Exercise


Solutions

Solutions Lab D Solutions

2232118Cycles

111227Code Size

Assembly Code

Optimized C Code

(-o3)

C Code


Appendix E – Control Law Accelerator

Introduction Appendix E discusses the details of the Piccolo™ TMS320F2803x Control Law Accelerator (CLA). The floating-point number format and the CLA registers will be discussed. Details of the CLA instruction set and pipeline will be explained. Additionally, system configuration and a comparison to the Delfino™ floating-point unit (FPU) will be covered.

Learning Objectives

Learning Objectives

Floating-point format

CLA registers and execution flow

Instructions

Pipeline

System configuration

Summary

C2000 Piccolo Workshop - Appendix E - Control Law Accelerator E - 1

Module Topics

Module Topics Appendix E – Control Law Accelerator ..................................................................................................E-1

Module Topics......................................................................................................................................... E-2 Control Law Accelerator ........................................................................................................................ E-3

Floating-Point Format......................................................................................................................... E-3 CLA Registers and Execution Flow ................................................................................................... E-4 CLA Instructions ................................................................................................................................ E-5 Status Register and Pipeline ............................................................................................................... E-6 CLA System Configuration ................................................................................................................ E-9 CLA Compared to C28x+FPU ......................................................................................................... E-11 Summary .......................................................................................................................................... E-12

E - 2 C2000 Piccolo Workshop - Appendix E - Control Law Accelerator



Floating-Point Format

IEEE Single-Precision Floating-Point Format

* Normal Positive and Negative Values are Calculated as: ( -1 ) s x 2 (E-127) x 1.M

+/- ~1.7 x 10 -38 to +/- ~3.4 x 10 +38

The Normalized IEEE numbers have a hidden 1; thus the equivalentsigned integer resolution is the number of mantissa bits + sign + 1

23-bit Mantissa (Implicit Leading Bit + Fraction Bits)8-bit Exponent (Biased)1 Sign Bit (0 = Positive, 1 = Negative) SS EE M M

Not a Number (NaN)Non-Zero255 (max)0 1Positive or Negative Infinity0255 (max)0 1Positive or Negative Values*0-0x7FFFF1-2540 1Denormalized NumberNon-Zero00 1Positive or Negative Zero000 1ValueMES

IEEE Single-Precision Floating-Point Format (IEEE 754)

Most widely used standard for floating-pointStandard number formats, Special values (NaN, Infinity)Rounding modes & floating-point operationsUsed on many CPUs

Simplifications for the C28x floating-point unitFlags & Compare Operations:

Negative zero is treated as positive zeroDenormalized values are treated as zeroNot-a-number (NaN) is treated as infinityRound-to-Zero Mode Supported (truncate)Round-to-Nearest Mode Supported (even)

These formats are commonly handled this way on embedded processors



CLA Registers and Execution Flow

CLA ExecutionRegisters

CLA ConfigurationRegisters

MR0 (32)MR1 (32)MR2 (32)MR3 (32)

MAR0MAR1MPC

MSTF (32)

toMVECT1

MVECT8

MCTL

MPISRCSEL1

MIFRMICLRMIFRC

MIOVFMICLROVF

MIERMIRUN

MEMCFG

Four 32-bit Result RegistersMR0 – MR3

MSTF: Status RegisterZero, negative, overflow, underflowRounding modeRPC: Return PC MEALLOW

Two 16-bit Auxiliary RegistersMAR0, MAR1Used for indirect addressing

MPC: 12-bit Program CounterOffset from the start of CLA program memoryIndicates instruction in the D2 phase

Eight Interrupt (Task) VectorsMVECT1 to MVECT8Offset from the start of CLA Program Memory to the beginning of the task

Interrupt/Task Source SelectionMPISRCSEL1:

Task1: ADCINT1 or EPWM1_INTTask2: ADCINT2 or EPWM2_INT….Task7: ADCINT7 or EPWM7_INTTask8: ADCINT8 or CPU Timer 0

MIER: Interrupt enable/disableMIRUN: Which task is running

Interrupt/Task ControlMIFR: FlagMICLR: ClearMIFRC: ForceMIOVF: Overflow flagMICLROVF: Overflow clear

Configuration and ControlMEMCFG: Memory configMCTL: CLA control

CLA Execution Registers:CSM ProtectedMain CPU has Read Only Access

CLA Configuration Registers:CSM and EALLOW ProtectedMain CPU has Read and Write Access

CLA Register Set

The task runs to completion(No task nesting)

x = Highest priority task both enabled and pending

PriorityTask1: Highest. . .

Task8: Lowest

Task request is via software or interrupt assigned in MPISRCSEL1:

Task1: ADCINT1 or EPWM1_INTTask2: ADCINT2 or EPWM2_INT…

Task7: ADCINT7 or EPWM7_INTTask8: ADCINT8 or CPU Timer 0

TaskRequest

?

Set MIOVF Bit(Overflow Flagged)

Set MIFR bit(Task Pending)

Yes

No

Yes

No

MIFRbit

Set?

The main CPU continues code execution in parallel with the CLA

Note: Software task requests will not set MIOVF

When a task completes a task-specific interrupt is sent to the PIE

Yes

Clear MIFR.x bitSet MIRUN.x bitMPC == MVECTx

Run CLA

TaskEnabled?

(MIER)

Yes

Yes

No

No

No

End ofTask?

MSTOP

TaskPending?

(MIFR)

Clear MIRUN.x bitTask x Interrupt to PIE

CLA Execution Flow



CLA Instructions

CLA Parallel Instructions

Multiply, Add, Subtract, MAC& Parallel Load

Multiply, Add, Subtract& Parallel Store

Multiply& Parallel Add/Subtract

Instruction


|| MMOV32 mem32,MRe

1MMPYF32 MRa,MRb,MRc

|| MSUBF32 MRd,MRe,MRf


|| MMOV32 MRe, mem32

CyclesExample

Both operations complete in a single cycle

Parallel bars indicate a parallel instructionParallel instructions operate as a single instruction with a single opcode and performs two operations

Example: Add + Parallel Store

MADDF32 MR3, MR3, MR1|| MMOV32 @_Var, MR3

; Before: MR0 = 2.0, MR1 = 3.0, MR2 = 10.0

MMPYF32 MR2, MR1, MR0 ; 1/1 instruction|| MMOV32 @_X, MR2

<any instruction>

; After: MR2 = MR1 * MR0 = 3.0 * 2.0; @_X = 10.0

Multiply and Store Parallel Instruction

Both the math operation and store complete in 1 cycleParallel Instruction:

MMOV32 uses the value of MR2 beforethe MMPY32 updates



Status Register and Pipeline

LVFLUFNFZFrsvd TF

CLA Status Register MSTF (32-bits)rsvdRND

F32rsvdRPC MEALLOW

CLA Status Flags

Call and return: MCNDD, MRCNDDUse store/load MSTF instructions to nest calls

Return Program Counter

RPC

Enable/disable CLA writes to “EALLOW”protected registers

Write ProtectionMEALLOW

To Zero (truncate) or To Nearest (even)Rounding ModeRNDF32

MTESTTF InstructionTest FlagTF

Float move operations to registers.Result of compare, min/max, absolute, negative Integer result of integer operations(MAND32, MOR32, SUB32, MLSR32 etc.)

Negative and Zero

ZFNF

Float math: MMPYF32, MADDF32, 1/x etc.Connected to the PIE for debug

Latched Overflow and Underflow

LVFLUF

Independent 8 Stage Pipeline

Fetch1: Program read address generatedFetch2: Read Opcode via CLA program data bus

Decode1: Decode instructionDecode2: Generate address

Conditional branch decision made MAR0/MAR1 update due to indirect addressing post increment

Read1: Data read address via CLA data read address busRead2: Read data via CLA data read data bus

Execute: Execute operationMAR0/MAR1 update due to load operations

Write: Write

All Instructions are single cycle (except for Branch/Call/Return)Memory conflicts in F1, R1 and W stall the pipeline

F2F1 D1 D2CLA PipelineFetch Decode

R1 R2 E W

Read Exe Write

CLA Pipeline Stages



MMOV32 @_Reg1, MR3 ; Write Reg1MMOV32 MR0, @_Reg2 ; Read Reg2

Due to the pipeline order, the read of Reg2 occurs before the Reg1 write

This is only an issue if the location written to can affect the location readSome peripheral registersWrite to followed by read from the same location

Insert 3 other instructions or MNOPs to allow the write to occur first


R1 R2 E W

Read Exe Write

Note: This behavior is different for the main C28 CPU:

The C28x CPU protects write followed by read to the same locationBlocks of peripheral registers have write-followed-by read protection

Write Followed-by-Read

Assume MAR0 is 50 and #_X is 20

MMOV16 MAR0, #_X ; I1 Load MAR0 with 20

MMOV32 MAR1, *MAR0[0]++ ; I2 Uses old MAR0 Value (50)MMOV32 MAR1, *MAR0[0]++ ; I3 Uses old MAR0 Value (50)

<Instruction 4> ; I4 Can not use MAR0MMOV32 MAR1, *MAR0[0]++ ; I5 Uses new MAR0 Value (20)


R1 R2 E W

Read Exe Write

D2: Update to MAR0/MAR1 due to indirect addressing post incrementEXE: Update to MAR0/MAR1 due to load operation

When instruction I1 is in EXE instruction I4 is in D2 If I4 uses MAR0, then a conflict will occur and MAR0 will not be loaded

Loading MAR0 and MAR1




R1 R2 E W

Read Exe Write

D2: Decide whether or not to branchEXE: Branch taken (or not)

* Can not be MSTOP (end of task), MDEBUGSTOP (debug halt), MBCNDD (branch), MCCNDD (call), or MRCNDD (return)

<Instruction 1> ; I1 Last instruction to affect flags for branch

<Instruction 2> ; I2 <Instruction 3> ; I3 <Instruction 4> ; I4

Branch, CND ; MBCNDD, MCCNDD or MRCNDD

<Instruction 5> ; I5<Instruction 6> ; I6<Instruction 7> ; I7

Can not be branch or stop *Do not change flags in time to affect branch

Can not be branch or stop *Always executed whether branch is taken or not

Branch, Call, Return Delayed Conditional

MCMPF32 MR0,#0.1MCMPF32 MR0,#0.01MTESTTF EQMNOPMBCNDD Skip1,NEQMMOV32 MR1,@_RampMMOVXI MR2,#RAMP_MASKMOR32 MR1,MR2MMOV32 @_Ramp,MR1...MSTOP

Skip1: MMOV32 MR3,@_SteadyMMOVXI MR2,#STEADY_MASKMOR32 MR3,MR2MBCNDD Skip2,NTFMMOV32 MR1,@_CoastMMOVXI MR2,#COAST_MASKMOR32 MR1,MR2MMOV32 @_Coast,MR1...MSTOP

Skip2: MMOV32 @_Steady,MR3...MSTOP

Optimized CodeMCMPF32 MR0,#0.1MNOPMNOP MNOP MBCNDD Skip1,NEQMNOPMNOPMNOPMMOV32 MR1,@_RampMMOVXI MR2,#RAMP_MASKMOR32 MR1,MR2MMOV32 @_Ramp,MR1...MSTOP

Skip1: MCMPF32 MR0,#0.01MNOP MNOP MNOP MBCNDD Skip2,NEQ MNOPMNOPMNOPMMOV32 MR1,@_Coast MMOVXI MR2,#COAST_MASKMOR32 MR1,MR2MMOV32 @_Coast,MR1...MSTOP

Skip2: MMOV32 MR3,@_SteadyMMOVXI MR2,#STEADY_MASKMOR32 MR3,MR2MMOV32 @_Steady,MR3...MSTOP

Cycle count variesdepending on delay

slot usage

447177

Not TakenTaken

MSTOP, MDEBUGSTOP

MBCNDD, MCCNDDMRCNDD are not allowed in delay

slots

6 instructionslots are

executed on every branch

Use these slots to improve

performance

Optimizing Delayed Conditional Branch



CLA System Configuration

C28 + CLASystem

InitializationCode

CLA RunTimeCode

Go

C Code

Assembly Code

C28 RunTimeCodeGo

CLA and Main CPU communication via

shared message RAMsand interrupts

Peripherals&

Memory

Access peripheral registers & memory

Configure

Access peripheral registers & memory

System initialization by the main CPU in C

CLA concurrently services time-critical

control loops

Main CPU performs communication,

diagnostics, I/O in C

Code Partitioning

<Instruction 1> ; I1

...

<Instruction 7> ; I7MUI16TOF32 MR0,@_AdcRegs.RESULT1

ADCConversion

RESULT Register Updates

After15 Cycles

CL

A M

ax B

andw

idth

= 2

6 C

ycle

s

ADC to CLAInterrupt Response

Latency6 Cycles

R ead AD C Reg

ADCSampleWindow7 Cycles

(minimum)

Assume 12 instructions12 cycles

Minimum CLA Next Task Response 5 cycles

Pre Calc (7 instructions)...

MSTOP ; 1 cycle

Perform pre-calculations using the first 7 instructions(7 cycles)

The 8th instruction is “just-in-time” to read the ADC RESULT register(1 cycle)

The ADC early interrupt occurs at the end of the sampling window

The CLA can read the result register as soon as it is latched

7 cycles after the early interrupt, the first CLA instruction is in the D2 phase of the pipeline

I1 in D2

I8 in R2

Timing shown for 2803x

RESULT register is latched and ready to be read

ADC’s early interrupt

Enables low ADC sample to output delay

“Just in Time” ADC Sampling Using CLA



ADCC28xCPU

PIE

SOCA/B

CLA

ADCINT1

ADCINT9ADCINT8

CLA

1_IN

T1

CLA

1_IN

T8

SOCA/B

EPWM1_INT/EPWM1_TZINT

EPWM7_INT7/EPWM7_TZINT

EPWM1_INT

EPWM7_INTLU

FLV

F

Piccolo ADC & CLA interrupt structure enables handling of multi-channel systems with different frequencies and/or phases

ePWM1

ePWM7

CLA Interrupts Improved Control Loop Timing

// File main.c#include “CLAShared.h”

#pragma DATA_SECTION(PIVars,"CpuToCla1MsgRAM");struct PI_CTRL PIVars;..// Use Symbols defined in the CLA asm fileCla1Regs.MVECT1 = (Uint16) (&Cla1Task1 \

- &Cla1Prog_Start)*sizeof(Uint32);

// Initialize variablesPIVars.KP = 1.234;PIVars.KI = 0.92367;PIVars.Ref = 2048.0;PIVars.I = PIVars.KP*PIVars.Ref;

..// Initialize Peripherals:Epwm3Regs.PRD = (Uint16) PERIOD;

// File: CLAShared.h

#include “DSP28x_Project.h”#define PERIOD 100.0struct PI_CTRL {

float KP;float KI;float I;float Ref;

} extern struct PI_CTRL PIVars;

extern Uint32 Cla1Prog_Start;extern Uint32 Cla1Task1;extern Uint32 Cla1Task2;etc …

// File: C28x_Project.h

#include “DSP2803x_Device.h”#include “DSP2803x_Examples.h”

Declare shared constants and variables in C

Include DSP2803x_Device.h to define register bit-field structures

Assign variables to message RAMs or CLA data memory sections using DATA_SECTION pragma

Add symbols defined in CLA assembly to make them global and usable in C

Using a shared C-code header file approach provides easy access to variables and constants in both C28x C and CLA assembly

Anatomy of CLA Code



; File: cla.asm; Include C Header File:

.cdecls C,LIST,”CLAShared.h”

; Add linker directives:.sect “Cla1Prog”

_Cla1Prog_Start:……_Cla1Task2:

MDEBUGSTOP ; breakpoint..; Read memory or register:MMOV32 MR0,@_PIVars.RefMUI16TOF32 MR1,@_AdcResult.ADCRESULT0MSUBF32 MR2,MR1,MR0..; Use constants defined in CMMPYF32 MR1,MR2,#PERIOD..; Write to memory or registerMMOV32 @_PIVars.I, MR3MMOV32 @_EPwm1Regs.CMPA.all, MR2..; End of taskMSTOP

_Cla1Task3:

Use .cdecls to include the shared C header file in the CLA assembly file// File: CLAShared.h

#include “DSP28x_Project.h”#define PERIOD 100.0struct PI_CTRL {

float KP;float KI;float I;float Ref;

} extern struct PI_CTRL PIVars;

extern Uint32 Cla1Prog_Start;extern Uint32 Cla1Task1;extern Uint32 Cla1Task2;etc …

Place CLA code into its own

assembly section

CLA assembly and C28 code reside in the same project

Put an MSTOP at the end of

the task

Use C header file references in

CLA assembly

Anatomy of CLA Code

CLA Compared to C28x+FPU

Single step flushes the pipelineSingle step moves the pipe one cycle

C28x + Floating-Point UnitControl Law Accelerator

Instructions Superset on Top of C28x Pass Data Between FPU and C28x Regs

Self-Contained Instruction SetData is Passed Via Message RAMs

Programmed in C/C++ or AssemblyProgrammed in Assembly

C28x Integer OperationsSupports Native Integer Operations:AND, OR, XOR, ADD/SUB, Shift

Uses C28x Branch, Call and ReturnCopy flags from FPU STF to C28x ST0Repeat MACF32 & Repeat Block

Native Delayed Branch, Call & Return Use Delay Slots to Do Extra WorkNo repeatable instructions

8 Result RegistersShares C28x Auxiliary RegistersSupports Stack, Nested Interrupts

4 Result Registers2 Independent Auxiliary RegistersNo Stack Pointer or Nested Interrupts

Uses C28x Addressing ModesNo Data Page Pointer; Only uses Direct & Indirect with Post-Increment

Math and Conversions are 2 CycleSingle Cycle Math and ConversionsF1-D2 Shared with the C28x PipelineIndependent 8 Stage Pipeline

CLA Compared to C28x+FPU



Summary

SummaryCLA is an independent 32-bit floating-point math accelerator

robust, self saturating, and easy to programSystem and CLA initialization is done by the CPU in CThe CLA can directly access:

ADC Result, ePWM+HRPWM and comparator registersThe CLA is interrupt driven and has a low interrupt response time (no nesting of interrupts)By using the ADC early interrupt, the CLA can read the sample “Just-in-time”

Reduced ADC sample to output delayFaster system response and higher MHz control loopsSupport for multi-channel loops


C28x Piccolo Workshop

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